Assessment of flood runoff and land cover changes in the Căinari river basin

Abstract

The present research is dedicated to assessment of flood runoff of the Căinari river situated in the northern part of the Republic of Moldova. A special attention is paid to evaluation of flood runoff temporal and spatial distribution and its changes due to different factors. Direct and indirect methods were used in order to perform the research tasks. General and statistical analysis was applied to estimate temporal evolution, trends, cycle fluctuations and to calculate statistical parameters and values of different return period of the Căinari river flood runoff characteristics measured at Sevirova station (1954-present). Spatial distribution of flood runoff and its changes due to land use management activities from the last 3 decades was performed using SCS-CN model. Analysis of temporal dynamics shows that in the last 60 years the trend of peak discharges is decreasing while the one of flood runoff depth is slowly increasing. Main flood runoff characteristics are: average peak discharge - 16.3 m3/s, depth - 4.41 mm, volume - 3.6 mln. m3, total duration - 9.0 days. Flood events monthly distribution is as follows: June – 34 %, July – 25 %, May – 14 %. Flood runoff modeling was performed for ungauged tributaries of the Căinari river in condition of equal rainfall of 100 mm, land cover for 1982 and 2013 and 3 soil moisture conditions: dry, wet and average. Average modeled flood runoff values are 58 mm, 28 mm in case of dry soil and 84 in case of wet soils. General dynamics shows that for the last 3 decades the flood runoff has slightly decreased due to increasing grassland and orchards areas and decreasing share of arable land.