| dc.description.abstract | Land use and land cover (LULC) change is one of the key driving elements responsible for altering the hydrology of a watershed. The stream flow has been highly fluctuating with prolonged hydrological drought. However little is known about the impact of land use/land cover changes on the water balance in Aswa river catchment In this study, the following objectives were addressed (1) To identify the quantitative and spatial change in land use/ land cover (2) To determine the quantitative and spatial changes in LULC changes between 2010-2020. And (3) To analyze the relationship between LULC changes and water balance in Aswa River catchment. For the land cover classification, three dry season Landsat images for 2010, 2015 and 2020 were acquired. Supervised classification was used in analysis of land-use/cover changes because it allows the user to define the training data set (or signature) that indicated the type of software and pixels to be selected for land-cover categories
The used water balance parameters were precipitation, transpiration, interception and evapotranspiration. These products were derived from the application of the process-based SEBAL (Chemura et al. 2020) In the SEBAL model, water fluxes are computed from satellite images and weather data using the surface energy balance. In order to understand how land cover change affect aspects of the water balance at catchment level, the study also linked remote sensing image classification with water flux in the catchment by examining the water balance equation parameters of interception, transpiration, evaporation and precipitation.
The result indicted that there was more precipitation interception, evaporation and transpiration occurred in areas which received more precipitation. This is because in areas that receive more rainfall are characterized with dense vegetation which increase interception and evapotranspiration. In terms of periods, interception and transpiration were higher in 2015 compared to 2010 and 2020 due to dense vegetation inform of forests and grass land as land cover and the low interception in 2020 was major caused by rapid reduction of the land cover, I also found out that throughout the study period, precipitation has continuously been the highest which ensures water availability as shown in figure 7, followed by transpiration. Precipitation and interception had the highest correlation with the water storage which implies that changes in the amounts of precipitation (r=0.838) and the interception (r=0.603) would highly affect the water storage (either increase or decrease it). It should also be noted that evaporation and transpiration had a negative correlation with water storage implying increase in any of the two would lead to a decline in the storage and vice vasa. Given that LULCC affects the water balance of an area, policies and strategies that protect the destruction of the ecosystem should be implemented to overcome undesired outcome of negative changes in water balance in the communities surrounded by the catchment.
In conclusion, the study demonstrate that land-use changes play an important role in water balance. And there were LULC changes in Aswa catchment which have greatly impacted the hydrology of the area (water flux). The study therefore recommends continuous monitoring of the water storage of the catchment through the monitoring of the amount of rainfall received in the area, streamflow of any outlet and conservation of natural vegetation | en_US |
