Strategy for controlling surface runoff in kemuning river basin, Indonesia

Abstract

Kemuning River flood every year and inundate the city of Sampang. Flood discharge is dominated by surface runoff. The Sungai Kemuning River Basin (DAS) is mostly (77%) in the form of gardens, fields and rice fields. The control of surface runoff is done by land conservation method, with the combination of 3 methods, namely: Vegetative, Mechanical, and Constructive Method.Conservation of vegetative methods, it is advisable to plant Mango or water apple with a combination of elephant grass (Pennisetum purpureum cv. Mott) in the garden, polowijo and elephant grass in the fields, and Paddy and Polowijo (one of: corn, soybeans, beans) in the fields. Mango and water apple is a local plant, but it is recommended to be updated with more superior varieties to be more productive. Elephant Grass is a new variety that is suitable to be planted in the watershed area, and it is intended to increase the stock of livestock feed, both cattle and goats. Conservation of mechanical methods, in the form of: making of infiltration holes and bench terraces in the garden, improving the design of embankments in fields and fields. The height of the embankment is reminded from 30 cm to 40 cm so as to increase the depth of the puddle in the fields from 0 cm to 30 cm, and the paddy field from 15 cm to 30 cm. With a land area of 20,526,430,000 m2 and a rice field of 1,183,356,100,000 m2, an increase in rainwater storage capacity of 793,296 m3 is obtained. This is identical with the capacity of two large dams. Conservation of constructive methods in the form of wells in the fields and rice fields. Recess wells are made in fields and rice fields with the amount and distribution of 1 unit per 2500 m2. The well serves as a recharge well to accelerate the decrease in the height of the normal puddle in the fields and in the rice fields. The peak flood discharge rates on the seven Sub-watersheds after conservation of land, respectively from Sub-DAS 1 to 7 are: 55%; 51%; 50%; 20%; 67%; 58%; 56%.