This paper analyses the possibilities of improving the precision of, and obtaining better, drainage density (Dd) input data for the Erosion Potential Method (EPM). This method is used for erosion assessments in karst areas that are characterised by torrential watercourses. The analysis is conducted in the Dubračina catchment in Croatia. Four different methodologies are used to derive a Dd map. The approaches use different assumptions and allow different spatial variability. The first two are commonly applied in the EPM. The Dd in the first case scenario corresponds to very low Dd and is homogenous throughout the entire catchment. In the second case, Dd is calculated on the sub-catchment level and varies from very low to medium. The third and fourth case scenarios provide the most spatially variant maps. The output of the third case is the actual Dd based on a topographic map, and the fourth potential Dd is based on a river network map derived from a Lidar digital elevation model. The third and fourth case scenarios provide better spatial variability for the Dd parameter, and both case scenarios are considered appropriate input data for the EPM and an improvement of the accuracy and precision of the EPM.

» Articles | Agricultural Journals

Krvavica, N.; Travaš, V., and Ožanić, N., 2017. Salt-wedge response to variable river flow and sea-level rise in the microtidal Rječina River Estuary, Croatia. A finite-volume model for two-layer shallow-water flow is presented and applied to study the dynamic response of a salt wedge in a microtidal estuary to changes in river flow rate and sea-level rise (SLR). First, the shape of the arrested salt wedge was computed for different hydrographic conditions. Next, the response of the salt wedge to highly variable river flow was investigated. Finally, this model was applied to predict the impacts of the SLR on salinity intrusions in the Rječina River Estuary. To assess the model performance and to examine the salinity structure in the estuary, a field-sampling campaign was conducted during 2014 and 2015. Field observations revealed negligible longitudinal density variations in both freshwater and saltwater layers and highly stratified conditions for all considered river flow rates and sea levels. F...