Valuasi ekonomi risiko bencana alam gerakan massa dan erosi terhadap lahan pertanian di DAS Tinalah Kulonprogo

KUMALAWATI, Rosalina, Dr. Junun Sartohadi, M.Sc

2005 | Tesis | S2 Geografi

Dampak Bencana Alam Gerakan Massa dan Erosi terhadap aspek fisik telah banyak di angkat, tetapi dampaknya terhadap aspek ekonomi belum banyak di teliti. Penelitian ini bertujuan untuk mengkaji persebaran tingkat risiko bencana alam gerakan massa dan erosi; mengkaji hubungan bencana alam gerakan massa dan erosi dengan kehilangan tanah, kehilangan unsur hara, dan penurunan hasil panen; untuk menyusun rekomendasi prioritas penanganan kerusakan lingkungan akibat bencana alam gerakan massa dan erosi. Pemilihan daerah penelitian ini menggunakan teknik purposive sampling, unit analisis di DAS Tinalah adalah unit lahan yang mengalami slide dan slump. Terdapat 57 unit lahan di DAS Tinalah, tetapi hanya 12 unit lahan yang mempunyai slide and slump. Setiap unit lahan di wakili 3-4 responden untuk wawancara. Penentuan sampel responden dilakukan menggunakan teknik random sampling dengan sistem undian. Teknik statistik korelasi di gunakan untuk analisis hubungan kehilangan tanah, kehilangan unsur hara, dan penurunan hasil panen. Hasil penelitian menunjukkan Banjarsari2 dan Purwoharjo mempunyai tingkat risiko bencana alam gerakan massa dan erosi tinggi. Gerakan massa dan erosi tanah tidak hanya berpengaruh pada kehilangan tanah dan kehilangan hara, tetapi juga pada penurunan hasil panen. Besarnya ”r” antara bencana alam dengan kehilangan tanah, bencana alam dengan kehilangan unsur hara, dan bencana alam dengan penurunan hasil panen adalah 0.014, 0.03, and 0.0135. Bencana alam berpengaruh pada kehilangan tanah dan kehilangan unsur hara walaupun nilai ”r” kecil. Bencana alam juga berpengaruh pada penurunan hasil panen walapun nilai ”r” tidak besar. Prioritas penanganan untuk mengurangi tingkat risiko bencana alam gerakan massa dan erosi lebih ditekankan pada penangulangan penurunan hasil panen.

The natural disaster impact of mass wasting and soil erosion on the phyisical aspects have commonly been investigated, however, its impact on the economical aspects have not much yet been investigated. This research was intended : to evaluate the spatial distribution of natural disaster risk of mass wasting and soil erosion; to evaluate the correlation between natural disaster risk of mass wasting with soil erosion and soil loss, soil nutrient loss, and agricultural product decline; to formulate the recommendation for controlling the environmental damages as the impact of mass wasting and soil erosion. The selection of the research area was established using purposive sampling techniques based on the occurrence of slide and slump in the land units located in Tinalah Watershed. There were 57 land units in Tinalah Watershed but only 12 land units have slide and slump. In every selected land units were taken 3- 4 respondents for interview. The respondents were chosen based on random sampling technique with lottery system. The correlation statistics technique was applied to analyze the relationships between soil loss, soil nutrient loss, and agricultural product decline. The results show that Banjarsari2 and Purwoharjo have high risk of natural disaster that include mass wasting and soil erosion. The mass wasting and soil erosion were not only influence the soil loss and soil nutrient loss, but also the agricultural product decline. The value of “r” between natural disaster with soil loss, natural disaster with soil nutrient loss, and natural disaster with agricultural product decline were 0.014, 0.03, and 0.135 respectively. Natural disaster had influents on soil loss and soil nutrient loss eventhough the “r” value was small. Natural disaster had influents on agricultural product decline eventhough the “r” value was not big. The priority of the efforts to reduce the risk of mass wasting and soil erosion should be put on the counter measure of agricultural product decline.

Kata Kunci : Geografi Fisik,Gerakan Massa dan Erosi Tanah,Lahan Pertanian, Valuation economic, correlation, mass wasting and soil erosion