Hidrogeomorfologi Mata Air Lembah Banjarasri Kecamatan Kalibawang Kabupaten Kulonprogo

ABSTRAK Mata air merupakan sumber air bersih potensial yang dimanfaatkan masyarakat di Lembah Banjarasri Kecamatan Kalibawang Kabupaten Kulonprogo. Tujuan penelitian ini adalah menganalisis karakteristik hidrogeomorfologi mata air di daerah penelitian. Kajian hidrogeomorfologi menjelaskan tentang aspek-aspek geomorfologi yang berpengaruh terhadap karakteristik pemunculan mata air pada setiap satuan bentuk lahan. Hasil penelitian menunjukkan bahwa secara geomorfologi di Lembah Banjarasri terdapat 2 mata air yang muncul pada bentuk lahan lerengkaki perbukitan struktural terdenudasi kuat, dengan debit aliran kecil, karena dipengaruhi oleh kemiringan lereng yang sangat curam, tipisnya lapisan tanah sebagai media infiltrasi air hujan, dan jenis material penyusun berupa batuan andesit tua yang relatif kedap air. Terdapat 12 mata air pada bentuk lahan lerengkaki perbukitan struktural terdenudasi sedang tersusun oleh batugamping Formasi Sentolo, berstruktur percelahan dan retakan, sehingga permeabilitas dan prorositas batuan tinggi dan berpotensi memunculkan mata air. Hanya terdapat 4 mata air yang muncul pada lerengkaki perbukitan struktural terdenudasi ringan, karena faktor material penyusun berupa batuan beku andesit tua Formasi Kebobutak. Pada bentuk lahan dataran aluvial terdapat 3 mata air, karena faktor topografi yang relatif datar hingga landai, dan tebalnya endapan aluvium, serta tidak ada kontrol struktur yang tegas sebagai faktor pemunculan mata air. Kata kunci: bentuk lahan, hidrogeomorfologi, mata air ABSTRACT Spring is the potential sources of clean water that is used by the community in the Banjarasri Valley, Kalibawang District, Kulonprogo Regency. The aim of this study was to analyze the spring hydrogeomorphological characteristics in the study area. The hydrogeomorphology study explains the geomorphological aspects that affect the characteristics of the appearance of springs in each existing landform unit. Results of the research show that in the Banjarasri valley there are 2 springs that appear on the slopes of the foothills, structurally strongly denuded, with small flow rates, because they are influenced by very steep slopes, the thin layer of soil as a medium for rainwater infiltration, and the type of constituent material in the form of old andesite rocks which are relatively massive and impermeable to water. There are 12 springs that appear on the slopes of the foothills, a moderately denuded structural structure composed of the Sentolo Formation limestones, which has many crevices and fractures structures, so that the permeability and porosity of the rock are high and have the potential to generate springs. There are only 4 springs that appear on the slopes of the foothills with a light denuded structure, due to the constituent material in the form of old andesite igneous rocks originating from the Kebobutak Formation. In alluvial plain landforms, there are 3 springs, due to the relatively flat to sloping topography, thick alluvium and colluvium deposits on the slopes, and there is no firm structural control as a strong factor causing the emergence of springs. Keywords: landform, hydrogeomorphology, spring