| Summary: | Deli Watershed is one of the critical watersheds in North Sumatra that
requires target priority for rehabilitation. Therefore, the guidance for conservation
and land use planning throughout sub watersheds of Deli watershed is need in
order to reduce the flood that always threatens the city of Medan. The purposes of
the research were: 1) to assess the biophysical characteristics of sub watersheds in
Deli watershed that may cause flooding in the city of Medan, 2) to assess the land
degradation in Deli watershed based on soil erosion predictions and soil erosion
hazard, degree of critical land, and land use capability of all sub watersheds, 3) to
design land conservation practice and land use planning of all sub watersheds of
Deli watershed to reduce land degradation, maximum discharge, and flood
volume of all sub watersheds. This study consisted of land degradation mapping,
and followed by filed verification in the form of biophysical survey. Mapping of
land degradation based on the soil erosion prediction and soil erosion hazard, the
critical level of land classification, land use capability classification, flood
analysis of Deli watershed. Verification is conducted in the target area of the land
units of the maps, i.e.: biophysical factors, actual conservation practices and later
on to be used for guidance of soil conservation planning that may able to decline
discharge and volume flood of sub watersheds of Deli watershed.
The results showed that land degradation of Deli watershed due to its
biophysical factors particularly land use change, slope, land form and rainfall as
well. Land degradation of Deli watershed caused by 1,293,764.9 tons of soil
erosion annually with average soil erosion 27.08 ton/ha/year, the rate of soil
erosion was as follows, Petani sub watershed 780,736.7 tons (average 60.9
ton/ha/year)
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