Quantifying drought and water scarcity: a case study in the Luanhe river basin

Abstract

Drought and water scarcity often occur simultaneously and are confused by water resources managers, because it is not easy to distinguish the two phenomena. In this study, we selected Luanhe river basin as the study area in which land use changed and a number of check dams were constructed. According to the situation in this river basin, we proposed the concepts of watershed drought (WD), watershed water scarcity (WWS) and streamflow water scarcity (SWS) based on the previous studies and made comparisons of the three concepts by a conceptual figure. A hydrological model was essential to separate the three concepts. Therefore, the Soil and Water Assessment Tool was calibrated and validated using hydrometeorological data and land surface data in undisturbed period in four sub-watersheds. Then the discharges in disturbed period were simulated under undisturbed and disturbed land use conditions without check dams, respectively. Compared with the variable threshold values, the features of WD, WWS and SWS were quantified. It was found that the mean duration of WD was the longest among the three phenomena and the maximum duration of WD could last more than 4 years. Water deficit caused by WD was the largest among the three phenomena, too, and it was about twice greater than water deficit caused by SWS in the four selected sub-watersheds. The method in this study is significant to separated drought and water scarcity in similar watersheds, and the results could provide significant information for water resources managers to make decision to predict drought and combat water scarcity.