Many people cannot distinguish between watersheds and rivers. They still think that the watershed is an area near the river. Even though the watershed coverage is not that narrow. In managing a watershed, it requires a deep understanding of the watershed itself.
The definition of DAS based on the function of a watershed is divided into several obstacles, firstly the upstream watershed is based on a conservation function which is managed to maintain the environmental conditions of the watershed so as not to experience degradation. The conservation function can be seen from the condition of watershed vegetation cover, water quality, ability to store water (discharge) and rainfall. Second, the middle watershed is based on the function of river water utilization which is managed so that it can provide benefits for social and economic interests, which can be seen, among others, from the quantity of water, water quality, ability to flow water and ground water. level, as well as related to irrigation infrastructure such as management of rivers, reservoirs, and lakes. Third, the downstream watershed is based on the function of utilizing river water which is managed so that it can provide benefits for social and economic interests, which is indicated by the quantity and quality of water, the ability to flow water, the height of rainfall, and related to agricultural needs, clean water, and management. waste.
Watershed management aims to prevent damage and repair damaged watersheds. Watershed management is carried out in accordance with three watershed functions, namely as a hydrological unit, landscape unit and ecosystem unit. As a hydrological unit, watershed as a place for the hydrological process to take place to convert inputs into outputs, functions as a single landscape unit. Watershed functions as a zone of conservation, production and habitat for living things, while as a place of interaction / linkage between components of the ecosystem is a function of the watershed as an ecosystem unit (Susetyaningsih, 2012). In each region, watershed management will differ depending on several factors, including the frequency of rainfall, vegetation characteristics, topography, soil types and geological characteristics. These factors will affect the morphometry, flow coefficient and vulnerability of a watershed as a hydrological function.
Indicators of success in watershed management based on hydrological functions can be seen from various aspects, one of which is the quantity and quality of water in the watershed. Water quality will affect everyone who uses water. Meanwhile, the quantity of water affects people, both those who use water, those who live in flood-prone areas, and those who depend on the river during the dry season. According to (Slamet, 2019), indicators that can be seen from a watershed for water quality and quality criteria are fluctuations in flow rate, annual water yield, total sediment load, water quality, and watershed response to rain consisting of runoff coefficients. , recession coefficient and concentration time).
The quantity and quality of water in the watershed can be determined from the morphometry, flow coefficient and watershed vulnerability. Watershed morphometry is related to the hydrological response received by a watershed in relation to flood prevention and prevention management. Flow coefficient is an indicator of surface runoff in a watershed and can be used as a benchmark to evaluate flow in relation to watershed management. The vulnerability of a watershed is related to the level of river water pollution due to sedimentation or other pollutants that can affect water quality, both surface and ground water.
In essence, a watershed is said to be healthy or well managed if the conditions of natural resource management activities are able to protect the needs of the community and watershed users and preserve its ecological functions (Suprayogo, 2011).