University of Twente Student Theses

Determination of the changes in annual and seasonal runoff and determine if the changes in runoff can be attributed to land cover change or climate change in the Merawu catchment, central Java.

Thus, D.J.H. (2023) Determination of the changes in annual and seasonal runoff and determine if the changes in runoff can be attributed to land cover change or climate change in the Merawu catchment, central Java.

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Abstract:	Deforestation has impacts on the water balance in tropical catchments. Deforestation tends to increase the annual discharge. However,a few studies have also shown that deforestation can result in lower runoff during the dry season. This is called the "sponge effect hypothesis". This hypothesis states that deforestation results in lower runoff during the dry season and higher runoff during the wet season. Currently there are still contradicting results regarding this hypothesis. The objective of this research is to determine the changes in annual and seasonal runoff and determine if these changes can be attributed to land cover changes or climate change. The study area is the Merawu catchment located on central Java, Indonesia. Firstly, the land cover classifications and the normalized difference vegetation index (NDVI) values have been determined by using satelite imageries of the Landsat and MODIS satellites. The mean areal rainfall (MAR) has been determined using the Thiessen polygon method. Subsequently, a Mann-Kendall trend test and Sen’s slope estimator have been used to determine the changes in annual and seasonal runoffs, rainfall and evapotranspiration. The land cover classifications indicate deforestation between 1992 and 2000 and afforestation between 2000 and2014. However, the accuracy of the land cover classifications is low, namely 66%. This results in uncertainty in the land cover changes found in this research. There have been no significant trends in the discharge of the catchment. A significantly positive trend has been found in the annual rainfall between 2000-2014. As this same trend has not been found in the discharge values this means that it is probable that there has also been a positive trend in actual evapotranspiration. No trend has been found in the average temperature of the Merawu catchment, which means that the plausible increase in actual evapotranspiration is not because of an increase in temperature due to climate change. Why the increase in precipitation has not resulted in an increase in discharge cannot be attributed to land cover change or climate change based of this research. To be able to do this, further research and an increase in the amount of quality data are necessary.
Item Type:	Essay (Bachelor)
Faculty:	ET: Engineering Technology
Programme:	Civil Engineering BSc (56952)
Link to this item:	https://purl.utwente.nl/essays/97383
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