Background: Even though wetlands are essential in enhancing water quality and providing recreation and entertainment opportunities in urban areas, their values are overlooked by the decision-makers. Underestimation of the economic value of wetland ecosystem services contributes to their continuing deterioration and inevitable loss. Investigating the changes in ecosystem service values (ESV) can provide crucial information for decision-making. This study, therefore, analyzes the temporal and spatial land-use/land-cover (LULC) change patterns over 35 years (1984–2019) intending to evaluate its impact on wetland ecosystem service values in Bahir Dar City, Ethiopia. Estimation and change analyses of ESVs were conducted by employing ArcGIS using LULC inputs of the year 1984, 1994, 2004, 2014, and 2019 with their corresponding global value coefficients that were developed earlier and our own modified value coefficients for the studied landscape. Results: The results showed that wetlands and water bodies of the city and its peripheries had decreased by 75.71% (−1618 ha) within 35 years, while built-up area increased by 216.24% (+2599 ha). Cultivated land had increased slightly from 1984 to 1994 and then gradually declined since 1994. Changes in LULC had resulted in a decline of the total ESV. The total ESV had decreased from USD 29.73 × 10⁶ to USD 20.84 × 10⁶ in 35 years. This indicates the loss of nearly USD 8.9 × 10⁶ ESV from 1984 to 2019. A sensitivity analysis suggested the robustness of ESV estimation in the study area. All individual ecosystem services experienced a negative change. However, a greater reduction in ESV was observed for services such as water regulation, waste treatment, and habitats for maintaining biodiversity. The expansion of built-up area of Bahir Dar City was the major factor that contributed to the loss of ESV provided by wetlands. Conclusions: The loss of ESV resulting in LULC changes has a negative implication on local climate, waste management, and the livelihoods of the poor community. Thus, interventions should be made for the restoration and sustainable management of wetlands in the urban and peri-urban areas of Bahir Dar City.

Water hyacinth has been progressively advanced in Lake Tana since 2011 and covered vast areas of the lakeshore. The aim of this study was to assess how the lakeshore covered by the weed mats affected the socioeconomic of the local community. The study was based on a survey of 405 households, 8 group discussions and interviews of 15 key informants conducted from January to March 2018. The results revealed that crop production, livestock feed supply, water supply, fishing, the health of local people and livestock were impacted negatively by the infestation of water hyacinth. The range of socioeconomic problems caused by the weed generally implied the real impacts on the lives of local communities and national economic development. The efforts made to control water hyacinth has costed huge labor and financial resources. The results revealed that close to 800,000 human labor dedicated to manual removal of the weed from 2012 to 2018 and above one million USD spent for procurement of harvester machines and bioagent experiments. In spite of the devotion of huge labor and spending of a lot of money, the expansion of the weed has not controlled. Poor coordination of controlling efforts, dumping of harvested dense mats of the weed in the lakeshore, lack of genuine participation of the local people are principal factors for the failure of the controlling efforts A coordination of various stakeholders thus is needed to make eradicating methods more effective. Other alternative options should also be considered to control the weed expansion.

Small-scale pond aquaculture has been practiced in various parts of the Lake Tana basin. However, its establishment and expansion have been carried out regardless of the suitability of the locations in terms of land, water, socioeconomic and other inputs available to the aquaculture development. In recent years, there is also an increased demand for aquaculture product, and the government and other private institutions have given much attention to the sector. In response to this need, it is necessary to evaluate the potential sites for aquaculture suitability based on biophysical and socioeconomic indicators. Consequently, GIS-based site suitability analysis was conducted at the basin level to identify and delineate areas, which are suitable for inland pond aquaculture, mainly for Nile Tilapia (Oreochromis niloticus). About 21 criteria, which are sub-grouped into socioeconomic, farm inputs and land use types, water availability, water and soil quality, and urban markets, were considered for aquaculture suitable site-selection analyses. They are converted into various thematic layers. The layers, then combined to develop their respective sub-model suitability maps, which in turn grouped to produce the final overall suitability maps using the weighted linear combination. The relative weights were generated through pairwise comparison by the analytical hierarchy process. The analysis indicates that the prevailing situation in the basin supports promising opportunity for the establishment and development of aquaculture. The GIS evaluation predicts that out of the total land identified for aquaculture site, 32,678.9 ha (2.7%) is highly suitable, whereas 1,166,594.5 ha (97.2%) is moderately suitable for small-scale pond aquaculture system. Similarly, the considerable part of the basin was moderately suitable with a total area of 1,183,253.0 ha (98.6%) and more than 1% (16,768.2 ha) was highly suitable for commercial aquaculture farming. The land area delineated for the marginally suitable category was negligible in both cases. Therefore, the result confirms that the Lake Tana basin has sizeable potential room for aquaculture development at small-scale and commercial production levels.

Developing multi-metric indices (MMIs) as a tool for inland water ecosystem assessment has attracted the attention of the global scientific community. The number of studies, which developed macroinvertebrate-based multi-metric indices for wetlands, however, was very limited. Thus, more work is needed to refine and implement it depending on the ecological contexts of wetlands. On top of this, we developed multi-metric indices based on macroinvertebrate assemblages that could be used for the ecological health assessment of wetlands that are impacted by agricultural activities in North-western Ethiopia. About 20 sampling sites were established in four wetlands along the disturbance gradient to take water and macroinvertebrates samples. The reference sites, which were least disturbed by human intervention, were established for the construction of multi-metric indices. Six core metrics were selected for the development of the final multi-metric indices from fifty-six potential metrics of macroinvertebrate assemblages after passing through sensitivity and statistical tests. The findings demonstrated all reference sites had good or high ecological conditions. On the contrary, the ecological statuses of nearly 70% of the impaired sites were found to be in bad to poor conditions. A significant distinction between reference and impaired sites suggested our index ability to identify the gradient variation in the ecological condition of wetlands. A strong negative relationship of the multi-metric indices model with most of the physicochemical variables and all human disturbance factors also suggested the appropriateness of the developed index in informing the ecological status of wetlands. Thus, we believe that our multi-metric indices could be a useful biomonitoring tool for the assessment and monitoring of wetland ecological conditions in predominantly agricultural landscapes in the Upper Blue Nile basin and beyond.

There is an increasing need globally to establish relationships among flow, ecology, and livelihoods to make informed decisions about environmental flows. This paper aimed to establish the ecological foundation for a holistic environmental flow assessment method in the Gumara River that flows into Lake Tana in Ethiopia and the Blue Nile River. First, the ecological conditions (fish, macro-invertebrate, riparian vegetation, and physicochemical) of the river system were characterized, followed by determining the hydrological condition and finally linking the ecological and hydrological components. The ecological data were collected at 30 sites along the Gumara River on March 2016 and 2020. River hydrology was estimated using the SWAT model and showed that the low flow decreased over time. Both physico-chemical and macroinvertebrate scores showed that water quality was moderate in most locations. The highest fish diversity index was in the lower reach at Wanzaye. Macroinvertebrate diversity was observed to decrease downstream. Both the fish and macroinvertebrate diversity indices were less than the expected maximum, being 3.29 and 4.5, respectively. The normalized difference vegetation index (NDVI) for 30 m and 60 m buffer distances from the river decreased during the dry season (March–May). Hence, flow conditions, water quality, and land-use change substantially influenced the abundance and diversity of fish, vegetation, and macroinvertebrate species. The pressure on the ecology is expected to increase because the construction of the proposed dam is expected to alter the flow regime. Thus, as demand for human water consumption grows, measures are needed, including quantification of environmental flow requirements and regulating river water uses to conserve the ecological status of the Gumara River and Lake Tana sub-basin.