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The Kilombero wetland in Tanzania is affected by advancing land use and land cover changes (LULCC), where we observe a conflict between development interests and the necessity of conservation measures to maintain the functionalities of the ecosystem. Thus, assessing patterns of LULCC is crucial to foresee potential future developments and to develop sustainable future management strategies. In this study, we use a multi-method scenario approach to assess the spatial implications and underlying driving forces of potential change by (1) developing a System Dynamics Causal Loop Diagram (CLD) to disentangle the underlying socio-economic and ecologic driving forces, (2) deriving a qualitative business-as-usual (BAU) and a conservation scenario from participatory narratives elaborated during a stakeholder workshop, and (3) quantifying the spatial implications of these scenarios with the Land Change Modeler (LCM). Results indicate that under the BAU assumption only 37% of the natural vegetation is expected to persist until 2030 in the wetland. In contrast, strict enforcement of protected areas (conservation scenario) halts further conversion of the wetland. However, both scenarios pinpoint considerable expansions of cropland in the western highlands with potentially serious impacts on catchment-wide hydrological processes. The produced qualitative and quantitative outputs reveal hotspots of possible future change and starting points for advisable further research and management interventions.
Katharina Proswitz; Mamkwe Edward; Mariele Evers; Felister Mombo; Alexander Mpwaga; Kristian Näschen; Jennifer Sesabo; Britta Höllermann. Complex Socio-Ecological Systems: Translating Narratives into Future Land Use and Land Cover Scenarios in the Kilombero Catchment, Tanzania. Sustainability 2021, 13, 6552 .
AMA StyleKatharina Proswitz, Mamkwe Edward, Mariele Evers, Felister Mombo, Alexander Mpwaga, Kristian Näschen, Jennifer Sesabo, Britta Höllermann. Complex Socio-Ecological Systems: Translating Narratives into Future Land Use and Land Cover Scenarios in the Kilombero Catchment, Tanzania. Sustainability. 2021; 13 (12):6552.
Chicago/Turabian StyleKatharina Proswitz; Mamkwe Edward; Mariele Evers; Felister Mombo; Alexander Mpwaga; Kristian Näschen; Jennifer Sesabo; Britta Höllermann. 2021. "Complex Socio-Ecological Systems: Translating Narratives into Future Land Use and Land Cover Scenarios in the Kilombero Catchment, Tanzania." Sustainability 13, no. 12: 6552.
The Kilombero Valley, one of East Africa’s largest seasonal wetlands, is a high-potential agricultural development corridor area in Tanzania. This seasonally flooded wetland is mainly used by smallholder farmers who cultivate during the rainy season, although there are some community-based irrigation systems that reduce hydro-climatic risks. In this study, we aim to understand how farmers’ aspirations and visions about the future are related to the current agricultural practices and human–water interaction. We specifically investigate the differences between farmers from rainfed and irrigated agriculture by using focus group discussions. Analysis of the in-depth interviews highlights how farmers’ actions both shape and respond to this highly dynamic and uncertain environment. Furthermore, we identify a close link, driven by the farmers’ level of agency, between aspirations and expected agro-economic development. The heterogeneity of farmers’ agency and hence their ability to cope with change is not only based on the socioeconomic status but also on their perception of the physical environment. We thus recommend that attention is also paid to the capacity for coping with environmental challenges that influences the level of farmers’ aspiration.
Britta Höllermann; Kristian Näschen; Naswiru Tibanyendela; Julius Kwesiga; Mariele Evers. Dynamics of Human–Water Interactions in the Kilombero Valley, Tanzania: Insights from Farmers’ Aspirations and Decisions in an Uncertain Environment. The European Journal of Development Research 2021, 1 -20.
AMA StyleBritta Höllermann, Kristian Näschen, Naswiru Tibanyendela, Julius Kwesiga, Mariele Evers. Dynamics of Human–Water Interactions in the Kilombero Valley, Tanzania: Insights from Farmers’ Aspirations and Decisions in an Uncertain Environment. The European Journal of Development Research. 2021; ():1-20.
Chicago/Turabian StyleBritta Höllermann; Kristian Näschen; Naswiru Tibanyendela; Julius Kwesiga; Mariele Evers. 2021. "Dynamics of Human–Water Interactions in the Kilombero Valley, Tanzania: Insights from Farmers’ Aspirations and Decisions in an Uncertain Environment." The European Journal of Development Research , no. : 1-20.
The Kilombero floodplain in Tanzania is one of the largest wetlands in Africa and at the same time one of the focus regions for agricultural production of the Tanzanian government. Whereas the floodplain received a lot of attention from the scientific community over the past years, little is known about the state of the entire catchment, in particular of its protected areas. We have evaluated how human impact – expressed here as land with specific anthropogenic land use (e.g. settlements, agricultural areas, teak plantations) – varies across the different protection categories (e.g. national park, game reserve, wildlife management area etc.). For that, first we used long-term land use/land cover (LULC) change maps of the Kilombero catchment to assess the human impact per protected area category. Second, we calculated building density per square kilometer as an indicator of existing human pressure. Third, from the anthropogenic LULC area in 2014 we predicted those areas that show similar morphometric, edaphic and bio-climatic conditions in the study region using the maximum-entropy algorithm (maxEnt). Results of the analysis reveal that in 2014 almost half of the Kilombero Ramsar site was covered by anthropogenic land uses, resulting in a share of 17% for all protected areas. Protected areas with strict use regulations such as national parks and game reserves showed virtually no anthropogenic land use throughout the observation period of 40 years (1974–2014), whereas LULC change was higher in unprotected areas. The increase of agricultural land was mainly at the expense of open woodland, floodplain grassland and savanna grassland. Our results further demonstrate that approx. 670.000 ha of the Kilombero catchment comprise similar conditions as the currently used land within the catchment. However, two thirds of it is located in protected areas, causing challenges for conservation. This is the first study exploring the effect of protected areas of the Kilombero catchment from a LULC and modeling perspective.
Frank Thonfeld; Stefanie Steinbach; Javier Muro; Konrad Hentze; Ian Games; Kristian Näschen; Pellage Francis Kauzeni. The impact of anthropogenic land use change on the protected areas of the Kilombero catchment, Tanzania. ISPRS Journal of Photogrammetry and Remote Sensing 2020, 168, 41 -55.
AMA StyleFrank Thonfeld, Stefanie Steinbach, Javier Muro, Konrad Hentze, Ian Games, Kristian Näschen, Pellage Francis Kauzeni. The impact of anthropogenic land use change on the protected areas of the Kilombero catchment, Tanzania. ISPRS Journal of Photogrammetry and Remote Sensing. 2020; 168 ():41-55.
Chicago/Turabian StyleFrank Thonfeld; Stefanie Steinbach; Javier Muro; Konrad Hentze; Ian Games; Kristian Näschen; Pellage Francis Kauzeni. 2020. "The impact of anthropogenic land use change on the protected areas of the Kilombero catchment, Tanzania." ISPRS Journal of Photogrammetry and Remote Sensing 168, no. : 41-55.
The impact of climate and land use/land cover (LULC) change continues to threaten water resources availability for the agriculturally used inland valley wetlands and their catchments in East Africa. This study assessed climate and LULC change impacts on the hydrological processes of a tropical headwater inland valley catchment in Uganda. The hydrological model Soil and Water Assessment Tool (SWAT) was applied to analyze climate and LULC change impacts on the hydrological processes. An ensemble of six regional climate models (RCMs) from the Coordinated Regional Downscaling Experiment for two Representative Concentration Pathways (RCPs), RCP4.5 and RCP8.5, were used for climate change assessment for historical (1976-2005) and future climate (2021-2050). Four LULC scenarios defined as exploitation, total conservation, slope conservation, and protection of headwater catchment were considered. The results indicate an increase in precipitation by 7.4% and 21.8% of the annual averages in the future under RCP4.5 and RCP8.5, respectively. Future wet conditions are more pronounced in the short rainy season than in the long rainy season. Flooding intensity is likely to increase during the rainy season with low flows more pronounced in the dry season. Increases in future annual averages of water yield (29.0% and 42.7% under RCP4.5 and RCP8.5, respectively) and surface runoff (37.6% and 51.8% under RCP4.5 and RCP8.5, respectively) relative to the historical simulations are projected. LULC and climate change individually will cause changes in the inland valley hydrological processes, but more pronounced changes are expected if the drivers are combined, although LULC changes will have a dominant influence. Adoption of total conservation, slope conservation and protection of headwater catchment LULC scenarios will significantly reduce climate change impacts on water resources in the inland valley. Thus, if sustainable climate-smart management practices are adopted, the availability of water resources for human consumption and agricultural production will increase.
Geofrey Gabiri; Bernd Diekkrüger; Kristian Näschen; Constanze Leemhuis; Roderick Van Der Linden; Jackson-Gilbert Mwanjalolo Majaliwa; Joy Apiyo Obando. Impact of Climate and Land Use/Land Cover Change on the Water Resources of a Tropical Inland Valley Catchment in Uganda, East Africa. Climate 2020, 8, 83 .
AMA StyleGeofrey Gabiri, Bernd Diekkrüger, Kristian Näschen, Constanze Leemhuis, Roderick Van Der Linden, Jackson-Gilbert Mwanjalolo Majaliwa, Joy Apiyo Obando. Impact of Climate and Land Use/Land Cover Change on the Water Resources of a Tropical Inland Valley Catchment in Uganda, East Africa. Climate. 2020; 8 (7):83.
Chicago/Turabian StyleGeofrey Gabiri; Bernd Diekkrüger; Kristian Näschen; Constanze Leemhuis; Roderick Van Der Linden; Jackson-Gilbert Mwanjalolo Majaliwa; Joy Apiyo Obando. 2020. "Impact of Climate and Land Use/Land Cover Change on the Water Resources of a Tropical Inland Valley Catchment in Uganda, East Africa." Climate 8, no. 7: 83.
At present, the seasonally flooded wetland of the Kilombero River is mainly used by small-scale farmers who predominantly produce rice and maize during the wet season. Some community-based irrigation systems do exist, which reduce the consequences and risks of climate variabilities regarding e.g. the onset of the rainy season and which allow year-round farming. Like other sub-Saharan wetlands, the Kilombero Valley floodplain is a highly dynamic environment, which is amplified due to increasing variability in the onset and intensity of the wet season.
In this study, we identify drivers of change and farmers’ decision-making strategies using focus group discussions with different types of farmers. In particular, we examine the differences between farmers from rain-fed and irrigated agriculture in terms of their agricultural practices and decision-making strategies for dealing with hydro-climatic risks. The results map the perceptions and visions of the people whose actions shape this highly dynamic environment and identify a range of options for action that go beyond the optimality paradigm.
Understanding how aspirations and visions about the future shape agricultural practices and hence human-water interaction is crucial to understand possible changes and dynamics of coupled socio-ecological systems. Therefore, this study is embedded into a wider multi-method approach integrating qualitative and quantitative data to inform and modify hydrological modelling. Here, the qualitatively collected data and findings of this research provide ground for developing additional scenarios for hydrological models and allow for contextualizing model results. Thus, human-water interactions can be better represented and the local populations’ perception and reactions to hydro-climatic risks can be assessed.
This research is part of the Collaborative Research Centre 228 “Rural Future Africa” funded by the German Research Foundation (DFG).
Britta Höllermann; Kristian Näschen; Naswiru Tibanyendela; Julius Kwesiga; Mariele Evers. Farmers’ decision-making strategies for dealing with hydro-climatic risks in the Kilombero Valley, Tanzania. 2020, 1 .
AMA StyleBritta Höllermann, Kristian Näschen, Naswiru Tibanyendela, Julius Kwesiga, Mariele Evers. Farmers’ decision-making strategies for dealing with hydro-climatic risks in the Kilombero Valley, Tanzania. . 2020; ():1.
Chicago/Turabian StyleBritta Höllermann; Kristian Näschen; Naswiru Tibanyendela; Julius Kwesiga; Mariele Evers. 2020. "Farmers’ decision-making strategies for dealing with hydro-climatic risks in the Kilombero Valley, Tanzania." , no. : 1.
The Kilombero catchment is a meso-scale catchment of 40,240 km² in south central Tanzania and is characterized by overall data scarcity like many other African catchments. The catchment consists of a highly dynamic floodplain system at its centre which is sustained by water from the surrounding uplands. It also contains a Ramsar site giving evidence to its valuable ecosystem and importance concerning biodiversity conservation. However, in the last decades land use and land cover changes (LULCC) accelerated drastically towards an agriculturally-shaped landscape, especially at the fringes of the wetland. The wetland system provides fertile soils, water as well as other water-related ecosystem services. Nevertheless, the increasing pressure on natural resources jeopardizes the sustainability of the socio-ecological system, especially in the face of climate change.
In this study, methods of hydrology, meteorology and remote sensing were used to overcome data-scarcity and gather a sound representation of natural processes in the catchment. The Soil and Water Assessment Tool (SWAT) was applied to represent the hydrological processes in the catchment. We utilized Landsat images from several decades to simulate the impact of LULCC from the 1970s until today. Furthermore, we applied the Land Change Modeller (LCM) to simulate potential LULCC until 2030 and their impact on water resources. To account for climatic changes, a regional climate model ensemble of the Coordinated Regional Downscaling Experiment (CORDEX) Africa project was analysed and bias-corrected to investigate changes in climatic patterns until 2060, according to the RCP4.5 (representative concentration pathways) and RCP8.5 scenarios.
The climate change signal indicates rising temperatures, especially in the hot dry season, which reinforces the special features of this season. However, the changes in precipitation signals among the analysed RCMs vary between -8.3% and +22.5% of the annual mean values. The results of the hydrological modelling also show heterogeneous spatial patterns within the catchment area. LULCC simulation results show a 6-8% decrease in low flows for the LULCC scenarios, while high flows increase by up to 84% for combined LULCC and climate change scenarios. The effect of climate change is more pronounced compared to the effect of LULCC, but also contains higher uncertainties. This study exemplarily quantifies the impact of LULCC and climate change in a data-scarce catchment and therefore contributes to the sustainable management of the investigated catchment, as it shows the impact of environmental change on hydrological extremes and determines hot spots, which are crucial for more detailed analyses like hydrodynamic modelling. The information from this study are an essential part to assist local stakeholders protecting the wetlands integrity on the one hand and to ensure sustainable agricultural practices in order to guarantee food security on the other hand in a catchment that has already changed tremendously and is still target to manifold future plans.
Kristian Näschen; Bernd Diekkrüger; Mariele Evers; Britta Höllermann; Larisa S. Seregina; Stefanie Steinbach; Frank Thonfeld; Roderick Van Der Linden. The impact of climate change and land use/land cover change on water resources in a data-scarce catchment in Tanzania. 2020, 1 .
AMA StyleKristian Näschen, Bernd Diekkrüger, Mariele Evers, Britta Höllermann, Larisa S. Seregina, Stefanie Steinbach, Frank Thonfeld, Roderick Van Der Linden. The impact of climate change and land use/land cover change on water resources in a data-scarce catchment in Tanzania. . 2020; ():1.
Chicago/Turabian StyleKristian Näschen; Bernd Diekkrüger; Mariele Evers; Britta Höllermann; Larisa S. Seregina; Stefanie Steinbach; Frank Thonfeld; Roderick Van Der Linden. 2020. "The impact of climate change and land use/land cover change on water resources in a data-scarce catchment in Tanzania." , no. : 1.
Many parts of sub-Saharan Africa (SSA) are prone to land use and land cover change (LULCC). In many cases, natural systems are converted into agricultural land to feed the growing population. However, despite climate change being a major focus nowadays, the impacts of these conversions on water resources, which are essential for agricultural production, is still often neglected, jeopardizing the sustainability of the socio-ecological system. This study investigates historic land use/land cover (LULC) patterns as well as potential future LULCC and its effect on water quantities in a complex tropical catchment in Tanzania. It then compares the results using two climate change scenarios. The Land Change Modeler (LCM) is used to analyze and to project LULC patterns until 2030 and the Soil and Water Assessment Tool (SWAT) is utilized to simulate the water balance under various LULC conditions. Results show decreasing low flows by 6–8% for the LULC scenarios, whereas high flows increase by up to 84% for the combined LULC and climate change scenarios. The effect of climate change is stronger compared to the effect of LULCC, but also contains higher uncertainties. The effects of LULCC are more distinct, although crop specific effects show diverging effects on water balance components. This study develops a methodology for quantifying the impact of land use and climate change and therefore contributes to the sustainable management of the investigated catchment, as it shows the impact of environmental change on hydrological extremes (low flow and floods) and determines hot spots, which are critical for environmental development.
Kristian Näschen; Bernd Diekkrüger; Mariele Evers; Britta Höllermann; Stefanie Steinbach; Frank Thonfeld. The Impact of Land Use/Land Cover Change (LULCC) on Water Resources in a Tropical Catchment in Tanzania under Different Climate Change Scenarios. Sustainability 2019, 11, 7083 .
AMA StyleKristian Näschen, Bernd Diekkrüger, Mariele Evers, Britta Höllermann, Stefanie Steinbach, Frank Thonfeld. The Impact of Land Use/Land Cover Change (LULCC) on Water Resources in a Tropical Catchment in Tanzania under Different Climate Change Scenarios. Sustainability. 2019; 11 (24):7083.
Chicago/Turabian StyleKristian Näschen; Bernd Diekkrüger; Mariele Evers; Britta Höllermann; Stefanie Steinbach; Frank Thonfeld. 2019. "The Impact of Land Use/Land Cover Change (LULCC) on Water Resources in a Tropical Catchment in Tanzania under Different Climate Change Scenarios." Sustainability 11, no. 24: 7083.
This article illustrates the impact of potential future climate scenarios on water quantity in time and space for an East African floodplain catchment surrounded by mountainous areas. In East Africa, agricultural intensification is shifting from upland cultivation into the wetlands due to year-round water availability and fertile soils. These advantageous agricultural conditions might be hampered through climate change impacts. Additionally, water-related risks, like droughts and flooding events, are likely to increase. Hence, this study investigates future climate patterns and their impact on water resources in one production cluster in Tanzania. To account for these changes, a regional climate model ensemble of the Coordinated Regional Downscaling Experiment (CORDEX) Africa project was analyzed to investigate changes in climatic patterns until 2060, according to the RCP4.5 (representative concentration pathways) and RCP8.5 scenarios. The semi-distributed Soil and Water Assessment Tool (SWAT) was utilized to analyze the impacts on water resources according to all scenarios. Modeling results indicate increasing temperatures, especially in the hot dry season, intensifying the distinctive features of the dry and rainy season. This consequently aggravates hydrological extremes, such as more-pronounced flooding and decreasing low flows. Overall, annual averages of water yield and surface runoff increase up to 61.6% and 67.8%, respectively, within the bias-corrected scenario simulations, compared to the historical simulations. However, changes in precipitation among the analyzed scenarios vary between −8.3% and +22.5% of the annual averages. Hydrological modeling results also show heterogeneous spatial patterns inside the catchment. These spatio-temporal patterns indicate the possibility of an aggravation for severe floods in wet seasons, as well as an increasing drought risk in dry seasons across the scenario simulations. Apart from that, the discharge peak, which is crucial for the flood recession agriculture in the floodplain, is likely to shift from April to May from the 2020s onwards.
Kristian Näschen; Bernd Diekkrüger; Constanze Leemhuis; Larisa S. Seregina; Roderick Van Der Linden. Impact of Climate Change on Water Resources in the Kilombero Catchment in Tanzania. Water 2019, 11, 859 .
AMA StyleKristian Näschen, Bernd Diekkrüger, Constanze Leemhuis, Larisa S. Seregina, Roderick Van Der Linden. Impact of Climate Change on Water Resources in the Kilombero Catchment in Tanzania. Water. 2019; 11 (4):859.
Chicago/Turabian StyleKristian Näschen; Bernd Diekkrüger; Constanze Leemhuis; Larisa S. Seregina; Roderick Van Der Linden. 2019. "Impact of Climate Change on Water Resources in the Kilombero Catchment in Tanzania." Water 11, no. 4: 859.
A combination of climate change, food demand, population growth, and other driving forces are causing land use and land cover change (LULC) in wetlands of Sub Saharan Africa (SSA). This has a profound effect on water resources, thus it is imperative that such consequences arising from these changes are predicted accurately to support land use management. For that, local scale studies are required to understand the system and to perform scenario analysis. The focus of this study was on small scale inland valleys which are common in SSA. The impact of LULC on the hydrological processes in a tropical inland valley was investigated. A hydrological response unit (HRU)-based (ArcSWAT2012) and a grid-based setup (SWATgrid) of the Soil Water Assessment Tool (SWAT) model are applied. Good model performance was achieved after calibration and validation with daily discharge (R2 and NSE > 0.7 for both model setups). Annual water balance indicates that 849.5 mm representing 65% of precipitation is lost via evapotranspiration. Surface runoff (77.9 mm) and lateral flow (86.5 mm) are the highest contributors to stream flow in the inland valley. Four land use management options are developed in addition to the current land use system, with different water resources conservation levels (Conservation, Slope conservation, Protection of headwater catchment, and Exploitation). There is a strong relationship between the first three management options with decreasing surface runoff, annual discharge and water yield while the fourth option will increase annual discharge and total water yield. This suggests that if poor management and increasing exploitation of the inland valleys persist, the availability of water resources for human consumption and plant growth will decrease. This study contributes to improving the scientific knowledge on the impact of land use change on hydrological processes in the catchment-wetland nexus to support sustainable water resources management.
Geofrey Gabiri; Constanze Leemhuis; Bernd Diekkrüger; Kristian Näschen; Stefanie Steinbach; Frank Thonfeld. Modelling the impact of land use management on water resources in a tropical inland valley catchment of central Uganda, East Africa. Science of The Total Environment 2018, 653, 1052 -1066.
AMA StyleGeofrey Gabiri, Constanze Leemhuis, Bernd Diekkrüger, Kristian Näschen, Stefanie Steinbach, Frank Thonfeld. Modelling the impact of land use management on water resources in a tropical inland valley catchment of central Uganda, East Africa. Science of The Total Environment. 2018; 653 ():1052-1066.
Chicago/Turabian StyleGeofrey Gabiri; Constanze Leemhuis; Bernd Diekkrüger; Kristian Näschen; Stefanie Steinbach; Frank Thonfeld. 2018. "Modelling the impact of land use management on water resources in a tropical inland valley catchment of central Uganda, East Africa." Science of The Total Environment 653, no. : 1052-1066.
This study investigates the effect of land use and land cover (LULC) and climate change on catchment hydrology and soil erosion in the Dano catchment in south-western Burkina Faso based on hydrological and soil erosion modeling. The past LULC change is studied using land use maps of the years 1990, 2000, 2007 and 2013. Based on these maps future LULC scenarios were developed for the years 2019, 2025 and 2030. The observed past and modeled future LULC are used to feed SHETRAN, a hydrological and soil erosion model. Observed and modeled climate data cover the period 1990–2030. The isolated influence of LULC change assuming a constant climate is simulated by applying the seven LULC maps under observed climate data of the period 1990–2015. The isolated effect of climate scenarios (RCP4.5 and 8.5 of CCLM4–8) is studied by applying the LULC map of 1990 to the period 1990–2032. Additionally, we combined past modeled climate data and past observed LULC maps. Two chronological and continuous simulations were used to estimate the impact of LULC in the past and in the future by gradually applying the LULC maps. These simulations consider the combined impact of LULC and climate change. The simulations that assumed a constant climate and a changing LULC show increasing water yield (3.6%–46.5%) and mainly increasing specific sediment yield (−3.3%–52.6%). The simulations that assume constant LULC and climate as changing factor indicate increases in water yield of 24.5% to 46.7% and in sediment yield of 31.1% to 54.7% between the periods 1990–2005 and 2006–2032. The continuous simulations signal a clear increase in water yield (20.3%–73.4%) and specific sediment yield (24.7% to 90.1%). Actual evapotranspiration is estimated to change by between −7.3% (only LUCC) to +3.3% (only climate change). When comparing observed LULC and climate change alone, climate change has a larger impact on discharge and sediment yield, but LULC amplifies climate change impacts strongly. However, future LULC (2019–2030) will have a stronger impact as currently observed.
Felix Op de Hipt; Bernd Diekkrüger; Gero Steup; Yacouba Yira; Thomas Hoffmann; Michael Rode; Kristian Näschen. Modeling the effect of land use and climate change on water resources and soil erosion in a tropical West African catch-ment (Dano, Burkina Faso) using SHETRAN. Science of The Total Environment 2018, 653, 431 -445.
AMA StyleFelix Op de Hipt, Bernd Diekkrüger, Gero Steup, Yacouba Yira, Thomas Hoffmann, Michael Rode, Kristian Näschen. Modeling the effect of land use and climate change on water resources and soil erosion in a tropical West African catch-ment (Dano, Burkina Faso) using SHETRAN. Science of The Total Environment. 2018; 653 ():431-445.
Chicago/Turabian StyleFelix Op de Hipt; Bernd Diekkrüger; Gero Steup; Yacouba Yira; Thomas Hoffmann; Michael Rode; Kristian Näschen. 2018. "Modeling the effect of land use and climate change on water resources and soil erosion in a tropical West African catch-ment (Dano, Burkina Faso) using SHETRAN." Science of The Total Environment 653, no. : 431-445.
Deterioration of upland soils, demographic growth, and climate change all lead to an increased utilization of wetlands in East Africa. This considerable pressure on wetland resources results in trade-offs between those resources and their related ecosystem services. Furthermore, relationships between catchment attributes and available wetland water resources are one of the key drivers that might lead to wetland degradation. To investigate the impacts of these developments on catchment-wetland water resources, the Soil and Water Assessment Tool (SWAT) was applied to the Kilombero Catchment in Tanzania, which is like many other East African catchments, as it is characterized by overall data scarcity. Due to the lack of recent discharge data, the model was calibrated for the period from 1958–1965 (R2 = 0.86, NSE = 0.85, KGE = 0.93) and validated from 1966–1970 (R2 = 0.80, NSE = 0.80, KGE = 0.89) with the sequential uncertainty fitting algorithm (SUFI-2) on a daily resolution. Results show the dependency of the wetland on baseflow contribution from the enclosing catchment, especially in dry season. Main contributions with regard to overall water yield arise from the northern mountains and the southeastern highlands, which are characterized by steep slopes and a high share of forest and savanna vegetation, respectively. Simulations of land use change effects, generated with Landsat images from the 1970s up to 2014, show severe shifts in the water balance components on the subcatchment scale due to anthropogenic activities. Sustainable management of the investigated catchment should therefore account for the catchment–wetland interaction concerning water resources, with a special emphasis on groundwater fluxes to ensure future food production as well as the preservation of the wetland ecosystem.
Kristian Näschen; Bernd Diekkrüger; Constanze Leemhuis; Stefanie Steinbach; Larisa S. Seregina; Frank Thonfeld; Roderick Van Der Linden. Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania. Water 2018, 10, 599 .
AMA StyleKristian Näschen, Bernd Diekkrüger, Constanze Leemhuis, Stefanie Steinbach, Larisa S. Seregina, Frank Thonfeld, Roderick Van Der Linden. Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania. Water. 2018; 10 (5):599.
Chicago/Turabian StyleKristian Näschen; Bernd Diekkrüger; Constanze Leemhuis; Stefanie Steinbach; Larisa S. Seregina; Frank Thonfeld; Roderick Van Der Linden. 2018. "Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania." Water 10, no. 5: 599.
Analyzing the spatial and temporal distribution of soil moisture is critical for ecohydrological processes and for sustainable water management studies in wetlands. The characterization of soil moisture dynamics and its influencing factors in agriculturally used wetlands pose a challenge in data-scarce regions such as East Africa. High resolution and good-quality time series soil moisture data are rarely available and gaps are frequent due to measurement constraints and device malfunctioning. Soil water models that integrate meteorological conditions and soil water storage may significantly overcome limitations due to data gaps at a point scale. The purpose of this study was to evaluate if the Hydrus-1D model would adequately simulate soil water dynamics at different hydrological zones of a tropical floodplain in Tanzania, to determine controlling factors for wet and dry periods and to assess soil water availability. The zones of the Kilombero floodplain were segmented as riparian, middle, and fringe along a defined transect. The model was satisfactorily calibrated (coefficient of determination; R2 = 0.54–0.92, root mean square error; RMSE = 0.02–0.11) on a plot scale using measured soil moisture content at soil depths of 10, 20, 30, and 40 cm. Satisfying statistical measures (R2 = 0.36–0.89, RMSE = 0.03–0.13) were obtained when calibrations for one plot were validated with measured soil moisture for another plot within the same hydrological zone. Results show the transferability of the calibrated Hydrus-1D model to predict soil moisture for other plots with similar hydrological conditions. Soil water storage increased towards the riparian zone, at 262.8 mm/a while actual evapotranspiration was highest (1043.9 mm/a) at the fringe. Overbank flow, precipitation, and groundwater control soil moisture dynamics at the riparian and middle zone, while at the fringe zone, rainfall and lateral flow from mountains control soil moisture during the long rainy seasons. In the dry and short rainy seasons, rainfall, soil properties, and atmospheric demands control soil moisture dynamics at the riparian and middle zone. In addition to these factors, depths to groundwater level control soil moisture variability at the fringe zone. Our results support a better understanding of groundwater-soil water interaction, and provide references for wetland conservation and sustainable agricultural water management.
Geofrey Gabiri; Sonja Burghof; Bernd Diekkrüger; Constanze Leemhuis; Stefanie Steinbach; Kristian Näschen. Modeling Spatial Soil Water Dynamics in a Tropical Floodplain, East Africa. Water 2018, 10, 191 .
AMA StyleGeofrey Gabiri, Sonja Burghof, Bernd Diekkrüger, Constanze Leemhuis, Stefanie Steinbach, Kristian Näschen. Modeling Spatial Soil Water Dynamics in a Tropical Floodplain, East Africa. Water. 2018; 10 (2):191.
Chicago/Turabian StyleGeofrey Gabiri; Sonja Burghof; Bernd Diekkrüger; Constanze Leemhuis; Stefanie Steinbach; Kristian Näschen. 2018. "Modeling Spatial Soil Water Dynamics in a Tropical Floodplain, East Africa." Water 10, no. 2: 191.
Inadequate knowledge exists on the distribution of soil moisture and shallow groundwater in intensively cultivated inland valley wetlands in tropical environments which are required for determining the hydrological regime. This study investigated the spatial and temporal variability of soil moisture along four hydrological positions segmented as riparian zone, valley bottom, fringe, and valley slope in an agriculturally used inland valley wetland in central Uganda. The determined hydrological regimes of the defined hydrological positions are based on soil moisture deficit calculated from the depth to the groundwater table. For that, the accuracy and reliability of satellite-derived surface models, SRTM-30 m and TanDEM-X-12m, for mapping microscale topography and hydrological regimes is evaluated against a 5m DEM derived from field measurements. Soil moisture and depth to groundwater table were measured using Frequency-Domain-Reflectometry sensors and piezometers installed along the hydrological positions, respectively. Results showed that spatial and temporal variability in soil moisture increased significantly (p<0.05) towards the riparian zone, however, no significant difference was observed between valley bottom and riparian zone. The distribution of soil hydrological regimes, saturated, near and non- saturated regimes does not correlate with the hydrological positions. This is due to high spatial and temporal variability in depth to groundwater and soil moisture content across the valley. Precipitation strongly controlled the temporal variability while microscale topography, soil properties, distance from the stream, anthropogenic factors, and land use controlled the spatial variability in the inland valley. TanDEM-X DEM reasonably mapped the microscale topography and thus soil hydrological regimes than SRTM DEM. The findings of the study contribute to improved understanding of the distribution of hydrological regimes in an inland valley wetland which is required for a better agricultural water management planning.
Geofrey Gabiri; Bernd Diekkrüger; Constanze Leemhuis; Sonja Burghof; Kristian Näschen; Immaculate Asiimwe; Yazidhi Bamutaze. Determining hydrological regimes in an agriculturally used tropical inland valley wetland in Central Uganda using soil moisture, groundwater, and digital elevation data. Hydrological Processes 2018, 32, 349 -362.
AMA StyleGeofrey Gabiri, Bernd Diekkrüger, Constanze Leemhuis, Sonja Burghof, Kristian Näschen, Immaculate Asiimwe, Yazidhi Bamutaze. Determining hydrological regimes in an agriculturally used tropical inland valley wetland in Central Uganda using soil moisture, groundwater, and digital elevation data. Hydrological Processes. 2018; 32 (3):349-362.
Chicago/Turabian StyleGeofrey Gabiri; Bernd Diekkrüger; Constanze Leemhuis; Sonja Burghof; Kristian Näschen; Immaculate Asiimwe; Yazidhi Bamutaze. 2018. "Determining hydrological regimes in an agriculturally used tropical inland valley wetland in Central Uganda using soil moisture, groundwater, and digital elevation data." Hydrological Processes 32, no. 3: 349-362.
Analysis and interpretation of soil properties dynamics is a keystone in understanding the hydrologic responses and yield potential of floodplain wetlands. This study characterizes the distribution and spatial trends of selected soil physical properties in the Kilombero floodplain, Tanzania. A total of 76 composite soil samples were taken from 0 to 20 cm and 20 to 40 cm depth in a regular grid design across three hydrological zones, related to flooding intensity defined as fringe, middle, and riparian during the rainy season of 2015. The samples were analyzed for soil texture, bulk density, organic carbon, and saturated hydraulic conductivity. Seasonal soil moisture content was monitored at depths of 10, 20, 30, and 40 cm, using 17 frequency domain reflectometry profile probes type PR2, installed at each hydrological zone for 18 months (March 2015–August 2016). Data were subjected to classical statistical and geostatistical analyses. Results showed significant (p < 0.05) differences in bulk density, texture, soil organic carbon (SOC), and saturated hydraulic conductivity (Ksat) across the hydrological zones. Bulk density showed a clear increasing trend towards the fringe zone. Mean Ksat was highest at the riparian zone (69.15 cm·d−1), and clay was higher in the riparian (20.3%) and middle (28.7%) zones, whereas fringe had the highest percentage of sand (33.7–35.9%). Geostatistical spatial results indicated that bulk density, silt, and SOC at 0–20 cm had intermediate dependence, whereas other soil properties at both depths had high spatial dependence. Soil moisture content showed a significant (p < 0.05) difference across the hydrological zones. The riparian zone retained the highest soil moisture content compared to the middle and fringe zone. The temporal soil moisture pattern corresponded to rainfall seasonality and at the riparian zone, soil moisture exhibited a convex shape of sloping curve, whereas a concave sloping curve for topsoil and for the middle zone at the subsoil was observed during the start of the dry season. Our results are seen to contribute to a better understanding of the spatial distribution of soil properties and as a reference for soil and water management planning in the floodplain.
Stephen Daniel; Geofrey Gabiri; Fridah Kirimi; Björn Glasner; Kristian Näschen; Constanze Leemhuis; Stefanie Steinbach; Kelvin Mtei. Spatial Distribution of Soil Hydrological Properties in the Kilombero Floodplain, Tanzania. Hydrology 2017, 4, 57 .
AMA StyleStephen Daniel, Geofrey Gabiri, Fridah Kirimi, Björn Glasner, Kristian Näschen, Constanze Leemhuis, Stefanie Steinbach, Kelvin Mtei. Spatial Distribution of Soil Hydrological Properties in the Kilombero Floodplain, Tanzania. Hydrology. 2017; 4 (4):57.
Chicago/Turabian StyleStephen Daniel; Geofrey Gabiri; Fridah Kirimi; Björn Glasner; Kristian Näschen; Constanze Leemhuis; Stefanie Steinbach; Kelvin Mtei. 2017. "Spatial Distribution of Soil Hydrological Properties in the Kilombero Floodplain, Tanzania." Hydrology 4, no. 4: 57.
Land Use Land Cover Change (LULCC) has a significant impact on water resources and ecosystems in sub-Saharan Africa (SSA). On the basis of three research projects we aim to describe and discuss the potential, uncertainties, synergies and science-policy interfaces of satellite-based integrated research for the Kilombero catchment, comprising one of the major agricultural utilized floodplains in Tanzania. LULCC was quantified at the floodplain and catchment scale analyzing Landsat 5 and Sentinel 2 satellite imagery applying different adapted classification methodologies. LULC maps at the catchment scale serve as spatial input for the distributed, process-based ecohydrological model SWAT (Soil Water Assessment Tool) simulating the changes in the spatial and temporal water balance in runoff components caused by LULCC. The results reveal that over the past 26 years LULCC has significantly altered the floodplain and already shows an impact on the ecosystem by degrading the existing wildlife corridors. On the catchment scale the anomalies of the water balance are still marginal, but with the expected structural changes of the catchment there is an urgent need to increase the public awareness and knowledge of decision makers regarding the effect of the relationship between LULCC, water resources and environmental degradation.
Constanze Leemhuis; Frank Thonfeld; Kristian Näschen; Stefanie Steinbach; Javier Muro; Adrian Strauch; Ander López; Giuseppe Daconto; Ian Games; Bernd Diekkrüger. Sustainability in the Food-Water-Ecosystem Nexus: The Role of Land Use and Land Cover Change for Water Resources and Ecosystems in the Kilombero Wetland, Tanzania. Sustainability 2017, 9, 1513 .
AMA StyleConstanze Leemhuis, Frank Thonfeld, Kristian Näschen, Stefanie Steinbach, Javier Muro, Adrian Strauch, Ander López, Giuseppe Daconto, Ian Games, Bernd Diekkrüger. Sustainability in the Food-Water-Ecosystem Nexus: The Role of Land Use and Land Cover Change for Water Resources and Ecosystems in the Kilombero Wetland, Tanzania. Sustainability. 2017; 9 (9):1513.
Chicago/Turabian StyleConstanze Leemhuis; Frank Thonfeld; Kristian Näschen; Stefanie Steinbach; Javier Muro; Adrian Strauch; Ander López; Giuseppe Daconto; Ian Games; Bernd Diekkrüger. 2017. "Sustainability in the Food-Water-Ecosystem Nexus: The Role of Land Use and Land Cover Change for Water Resources and Ecosystems in the Kilombero Wetland, Tanzania." Sustainability 9, no. 9: 1513.
Wetlands cover an area of approx. 18 Mio ha in the East African countries of Kenya, Rwanda, Uganda and Tanzania, with still a relative small share being used for food production. Current upland agricultural use intensification in these countries due to demographic growth, climate change and globalization effects are leading to an over-exploitation of the resource base, followed by an intensification of agricultural wetland use. We aim on translating, transferring and upscaling knowledge on experimental test-site wetland properties, small-scale hydrological processes, and water related ecosystem services under different types of management from local to national scale. This information gained at the experimental wetland/catchment scale will be embedded as reference data within an East African wetland-catchment data base including catchment physical properties and a regional wetland inventory serving as a base for policy advice and the development of sustainable wetland management strategies.
Constanze Leemhuis; Esther Amler; Bernd Diekkrüger; Geofrey Gabiri; Kristian Näschen. East African wetland-catchment data base for sustainable wetland management. Proceedings of the International Association of Hydrological Sciences 2016, 374, 123 -128.
AMA StyleConstanze Leemhuis, Esther Amler, Bernd Diekkrüger, Geofrey Gabiri, Kristian Näschen. East African wetland-catchment data base for sustainable wetland management. Proceedings of the International Association of Hydrological Sciences. 2016; 374 ():123-128.
Chicago/Turabian StyleConstanze Leemhuis; Esther Amler; Bernd Diekkrüger; Geofrey Gabiri; Kristian Näschen. 2016. "East African wetland-catchment data base for sustainable wetland management." Proceedings of the International Association of Hydrological Sciences 374, no. : 123-128.