Water Yield Analysis on Area Coveredby Pine Forest at Kedungbulus Watershed Central Java, Indonesia

Abstract

The analysis of water yield is conducted to provide information on the availability of water resources at a particular location in a watershed. Kedungbulus watershed is located in an area with plantation of pine forest. The pine forest area varies from 7% to 95% of the sub watershed areas. The plantation of this kind of vegetation (Pinusmerkusii) in some regions may cause water availability problem due to it may consume much more water rather than others. The objective of this study is to analyze the effect of pine forest area and its characteristics on the water yield in several of sub watershed at Kedungbulus Watershed. Direct measurement and prediction were used to estimate the water yield. A Thorthwaiteand Mather method was used in this study to estimate the water yield. It was completed with data of rainfall, air temperature, soil properties, and land cover. Stand density varies from 388 to 644 stand/hectare and diameter at breast height (DBH) varies from 20 to 40 cm. The annual rainfall during the year of 2015 at the location was 2525 mm. It was found that the water yield tends to decrease with the increase of pine forest area. The water yield of the watershed with pine forest covered with 7% was 1520 mm/year, while watershed with pine forest covered 95% was lower (1289 mm/year). In order to increase the water yield, the pine forest plantation is not recommended in a certain area with low rainfall. Modified Thorthwaite-Mather Water Balance method was successfully applied to this case with a significant increase in determination coefficient from 0.3 to 0.7.

Assessment of the Impacts of Climate and LULC Changes on the Water Yield in the Citarum River Basin, West Java Province, Indonesia

“…The same change may have different impacts on WY, according to [49], whose research revealed that several findings do not show natural variability consistently. For example, deforestation increases WY [36,39,50] in China, in Indonesia [51], in Australia, the USA, Africa, and Germany [52], in Pakistan [53], in Malaysia [54], in Africa [55,56], and in Ecuador [41].…”

Biomass carbon stock and water yield of teak catchments

“…In tropical to subtropical region of Xishuangbanna in China, have examined data from 1976 to 2012 and have found that conversion of native forest and expansion around 20 times of plantation in the study area resulted in decreasing carbon stock by 45% and water yield by 32%. In addition, the decrease in water yield due to the increase plantation areas were also observed by Pramono et al (2017) in pine catchments and Basuki and Pramono (2020) in teak plantation catchments in the tropical region, Indonesia. The decrease in water yield at large plantation areas is caused by evapotranspiration (Price, 2011); however, Bruijnzeel (2004) has observed that the decrease in water yield is more triggered by soil compaction which reduces infiltration and dry season flow.…”

Reforestation and Sustainable Management of Pinus merkusii Forest Plantation in Indonesia: A Review

“…Sumatran pine forests affect fluctuations of groundwater level. A farther distance will result in a greater fluctuation with the value of coefficient determination (r2) reaching 0.73 [127]. However, another study showed that the Sumatran pine forest also consumed more water than other commodities (i.e., rice fields, mixed gardens, and agricultural fields) [126].…”