Analysis of Vegetation Density Effect In Bengawan Solo Watershed To The Total Suspended Solid (TSS) In Gajah Mungkur Reservoir

Abstract

Gajah Mungkur Reservoir located in Wonogiri Regency Central Java Province. This is a multipurpose reservoir with an area of approximately 8,800 ha. This reservoir can irrigate 23.600 ha of rice fields in Sukoharjo, Klaten, Karanganyar and Sragen districts. The amount of sedimentation increased rapidly resulting in degradation of water quality of Gajah Mungkur Reservoir. High sedimentation can be shown from the high value of Total Suspended Solid (TSS) in the waters. TSS is a solid material, including organic and inorganic matter suspended in aquatic area. TSS Dynamics in the waters of Gajah Mungkur Reservoir can not be separated from the dynamics of vegetation density change in Watershed area (DAS). The watershed that flows into the Gajah Mungkur Reservoir is Bengawan solo Watershed.Total Suspended Solid (TSS) concentration can be identified using Total Suspended Solid (TSS) algorithm in Landsat 8 Satellite imagery. This research is monitored by TSS development in 2013, 2015, and 2017 which then compared with TSS level in the field. Vegetation density was identified using the Normalized Difference Vegetation Index (NDVI) method.Based on the results obtained the most suitable algorithm in the waters of Gajah Mungkur Reservoir is TSS Syarif Budhiman algorithm with 92% regression coefficient. The concentration of TSS in the waters of Gajah Mungkur Reservoir in the period of 2013-2017 has increased. Then the result of vegetation density in Bengawan Solo watershed showed that dominates is a fairly tight class. While the density of vegetation in the watershed that flows into the Gajah Mungkur Reservoir in 2013-2017 significant changes also some Sub watershed that decreased vegetation density occurred in the sub watershed Keduang, Solo Hulu and Wuryantoro. The vegetation density of several sub watersheds has an effect on the content of TSS in Gajah reservoir at estuary of the sub-watershed.