Abstract
Soil and water resources are vital to a society because these resources maintain the environment and living being. Understanding the inconsistencies of these resources has significant importance for regional planning and landscape management. Though their relevance, there is no updated data and organized method for characterization and mapping of soil database and hydrological system in Abha watershed area. The objective of this study is to develop a soil geodatabase and generation of hydrological zones. The methodology is based on the Geoinformatics techniques to determine the causative factors that affect the hydrology and to delineate hydrological zones. Ten parameters were considered to delineate the hydrological zones based on the literature review and thorough discussion with international scientific experts (i.e., engineers, hydrologists, and hydrogeologists). The themes and their classes were assigned suitable weights on Saaty's scale according to their relative importance. The assigned weights of the themes and their classes were normalized by analytic hierarchy process and eigenvector method. Thereafter, the all themes were integrated in geographical information system (GIS) using weighted linear combination method to create the hydrological map. Thus, five hydrological zones were identified and demarcated in the study area, viz. "very low runoff," "low runoff," "moderate runoff," "high runoff," and "very high runoff" based on surface runoff potential index values. This analysis also shows that 5.09 and 32.29 % of the watershed lies in the very high runoff and high runoff zone, followed by moderate and low runoff zone with 28.17 and 25.22 % areal coverage, respectively. With this qualitative-based classification, the high runoff generation area of the Abha watershed has a large area coverage, indicating the availability of high surface water potential. Additionally, the results showed that the runoff distribution in the western, southwestern, and central north highlands of the watershed is high and these areas flow to the down wadies. Thus, the contribution of this work in understanding the Abha watershed hydrologic system is significant. The results provide valuable information of Abha watershed about the hydrological zone and soil database at a large scale for the first time. Generated maps will assist to formulate effective runoff utilization plans so as to ensure long-term sustainability.