THE VALUE OF INITIAL ABSTRACTION AND ESTIMATION OF RUNOFF-FORMING RAINFALL RATE AT A SPECIFIC GEOGRAPHICAL LOCATION

Abstract

The changes of precipitation and temperature under different scenarios influence on the humidity condition of the territory (HCT) by various effect types. Therefore, when assessing the rate of runoff formation process, water resources and natural risks, is considered a key factor the HCT. At present, there is the tendention in world hydrology science the HCT is estimated mainly on the basis of 3 parameters ─ maximum retention (S), initial abstraction (Ia ) and antecedent moisture condition (AMC). S─is the potential maximum moisture retention of the territory in a concrete physico-geographical condition, Ia ─is the fraction of the precipitation (P) on the moistening of various surface types and other losses before runoff begins, AMC-reflects the previous humidity condition of territory at the moment rainfall beginning and 3 AMC rates are determined (avarage, dry, saturated). In accordance with the runoff formation conditions, the southern slope of the Greater Caucasus are divided into 11 humidity zones. For each of the zones considering 3 AMCs, it’s possible to estimate water resources, runoff generation level and losses, S, Ia and other water balance components for both the multi-annual term and the specific period. The calculations may be realized easily both by the analysis of multispectral satellite images of the territory using rational method, and by the relationships S=f(P) and Ia=f(S) offered by us. The research results are obtained by processing of complex runoff-forming factors using GIS technology, there are high accuracy and their application is possible in solution the major water-related issues.