The The Effect of Land use Changes on Runoff Discharge in Ampenan and Sekarbela District, Mataram City

Changes in land use in Ampenan and Sekarbela Districts in the Mataram city area have occurred on a massive scale. The high level of infrastructure development and increasing population density has caused the area of ​​green land to decrease and the built-up area to increase. This change in land function affects the land's ability to absorb rainwater that falls in an area. This research was conducted to determine the runoff discharge that occurred due to changes in land use in 2013, 2018 and 2023, and to compare the runoff discharge in 2023 with the runoff discharge based spatial plans on the 2011-2031. The analysis stage begins with water catchment area delineation and land use analysis with the help of ArcMap and Google Earth software. Then proceed with the calculation of runoff coefficient values, analysis of regional rainfall, analysis of rainfall plans, calculation of rain intensity, calculation of runoff discharge using rational methods and comparing runoff discharge that occurs in 2023 with runoff discharge based spatial plans on the 2011-2031. The research results show that there is a decrease in the area of ​​green land and an increase in the area of ​​built-up land which causes the runoff coefficient and runoff discharge values ​​to increase. The increase in runoff discharge in Sekarbela District in 2013-2018 was 6.52%, in 2018-2023 was 2.81%, and in 2013-2023 was 9.52%. Meanwhile, the increase in runoff discharge in Ampenan District in 2013-2018 was 3.02%, in 2018-2023 was 2.10%, and in 2013-2023 was 5.18%.