scholarly journals Spatial Modeling of Sediment Export Rate with Rainfall Variability Scenario in Peusangan Watershed, Aceh Province

2021 ◽  
Vol 925 (1) ◽  
pp. 012026
Author(s):  
E Djunarsjah ◽  
M M Julian ◽  
A A Baskoro ◽  
N R Alfandi

Abstract The rainfall affects the environmental interaction of watersheds and coastal areas. The high intensity of rain and water runoff will lift and carry particles in the watershed environment in the erosion process. This study estimates the total exports of sediment in Peusangan Watershed in the period 1995, 2005, 2015, and 2018 with rainfall variability scenarios. Total sediment exports are calculated from the erosion rate and sediment delivery ratio (SDR). Erosion rate modeling uses the RUSLE (Revised Universal Soil Loss Equation) that takes into account erosivity of rainfall, soil erodiability, topography, land cover, and land-use practices. While SDR is calculated based on its function as watershed area so that homogeneous value that causes the value of sediment export rate is directly proportional to the erosion rate value. The correlation between rainfall variability and sediment export rates is calculated based on rainfall variability correlation to erosion rate change. There is a direct relationship between rainfall variability and sediment export rates because the correlation coefficient is close to one. The rate of erosion in Peusangan watersheds falls into the light category based on the classification of erosion hazard levels according to the Ministry of Forestry in 1998. Based on the estimated rate of erosion and SDR, the total annual number of sediment exports obtained in the Peusangan watershed in 1995, 2005, 2015, and 2018 amounted to 1,066,027,426 tons, 909,914,623 tons, 1,075,759,133 tons, and 1,085,490,841 tons, respectively. Based on the spatial distribution of sediment export, Peusangan Watershed falls into the category of normal erosion.

2021 ◽  
Vol 925 (1) ◽  
pp. 012029
Author(s):  
E Djunarsjah ◽  
M M Julian ◽  
N R Alfandi ◽  
A A Baskoro

Abstract The watershed is an area above or higher than a river whose topographical boundaries cause water to flow into the same river. The river flow carries sediment particles that potentially cause silting of the estuary area. The sediment carried by the river flows from the erosion process that occurs in the watershed. Changes in land cover potentially affect the rate of sediment export to rivers due to changes in surface roughness and water infiltration rate to the ground. This study aims to identify the effect of the land cover change on the total sediment yield from the Peusangan Watershed, Aceh Province. The sediment yield is calculated from the erosion rate and the sediment delivery ratio. The erosion rate is modeled using the revised universal soil loss equation, while the sediment delivery ratio is calculated based on the function of the watershed area. From the results of the calculation, in general, the rate of erosion is at a very level where the average erosion rate in 1995 is 26,715 tons/ha/year, in 2005 it is 26,886 tons/ha/year, in 2015 it is 24,959 tons/ha/year and in 2018 amounted to 26,771 tons/ha/year. With a sediment delivery ratio value of 0.180, The total sediment yield was 1,083,148.20 tons in 1995, 1,090,047.94 tons in 2005, 1,011,920.71 tons in 2015, and 1,085,398.35 tons in 2018. The identification results show that the changes in land cover affect the total sediment yield that comes out of the watershed.


2019 ◽  
Author(s):  
Abreham Berta Aneseyee

Abstract Background: Information on soil loss and sediment export is essential to identify hotspots of soil erosion for conservation interventions in a given watershed. This study aims at investigating the dynamic of soil loss and sediment export associated with land use/land cover change and identifies soil loss hotspot areas in Winike watershed of Omo-gibe basin of Ethiopia. Spatial data collected from satellite images, topographic maps, meteorological and soil data were analyzed. Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) of sediment delivery ratio (SDR) model was used based on analysis of land use/land cover maps and RUSLE factors. Result: The results showed that total soil loss increased from 774.86 thousand tons in 1988 to 951.21 thousand tons in 2018 while the corresponding sediment export increased by 3.85 thousand tons in the same period. These were subsequently investigated in each land-use type. Cultivated fields generated the highest soil erosion rate, which increased by 10.02 t/ha/year in 1988 to 43.48 t/ha/year in 2018. This corresponds with the expansion of the cultivated area that increased from 44.95 thousand ha in 1988 to 59.79 thousand ha in 2018. This is logical as the correlation between soil loss and sediment delivery and expansion of cultivated area is highly significant (p<0.01). Sub-watershed six (SW-6) generated the highest soil loss (62.77 t/ha/year) and sediment export 16.69 t/ha/year, followed by Sub-watershed ten (SW-10) that are situated in the upland plateau. Conversely, the lower reaches of the watershed are under dense vegetation cover and experiencing less erosion. Conclusion: Overall, the changes in land use/land cover affect significantly the soil erosion and sediment export dynamism. This research is used to identify an area to prioritize the watershed for immediate management practices. Thus, land use policy measures need to be enforced to protect the hydropower generation dams at downstream and the ecosystem at the watershed.


Author(s):  
Souad Ben Salem ◽  
Abdelkrim Ben Salem ◽  
Ahmed Karmaoui ◽  
Mohammed Khebiza Yacoubi ◽  
Mohammed Messouli

The Ziz Watershed is located in the arid zones of South-Eastern Morocco and belongs to the large basin of Ziz-Rheris. In this basin, floods are related to natural factors and mainly to the occupation of the hydraulic public domain and the human intervention on the courses of the rivers. Increases in sediment yield are observed in many places in the Ziz, dramatically affecting water quality and reservoir management. In order to map overland sediment generation and delivery to the stream (studying the service of sediment retention), the InVEST sediment delivery ratio (SDR) model was applied. The sedimentation analysis in the Hassan Dakhil Dam, located in this watershed, shows that there is a very important erosion rate. The proof is the rapid filling of the dam. This is due to the transport of sediments in the rivers. If this situation continues at the current rate, the dam will no longer be fully operational for irrigation by 2050.


2018 ◽  
Author(s):  
Poerbandono ◽  
agung budi harto ◽  
Miga Magenika Julian

This paper discusses the development and application of a spatial tool for erosion modeling named Spatial Decision Assistance of Watershed Sedimentation (SDAS). SDAS computes export (yield) of sediment from watershed as product of erosion rate and sediment delivery ratio (SDR). The erosion rate is calculated for each raster grid according to a digital elevation model, soil, rain fall depth, and land cover data using the Universal Soil Loss Equation. SDR calculation is carried out for each spatial unit. A spatial unit is the smallest sub-watershed considered in the model and generated according to the TauDEM algorithm. The size of one spatial unit is assigned by the user as the minimum number of raster grids. SDR is inversely proportional to sediment resident time and controlled by rainfall, slope, soil, and land cover. Application of SDAS is demonstrated in this paper by simulating the spatial distribution of the annual sediment yield across the Citarum watershed in the northwest of Java, Indonesia. SDAS calibration was carried out based on sediment discharge observations from the upper catchment. We considered factors for hillslope flow depth and for actual and effective rainfall duration to fit the computed sediment yield to the observed sediment discharge. The computed sediment yield agreed with the observation data with a 7% mean relative accuracy.


2002 ◽  
Vol 82 (4) ◽  
pp. 423-431 ◽  
Author(s):  
L. Mabit ◽  
C. Bernard ◽  
M R Laverdière

The intensification and specialization of agriculture that took place in the past decades have resulted in soil and water degradation in several areas of eastern Canada. Most studies on soil erosion in Quebec have been conducted at the experimental plot scale. Although this approach generates precise data, extrapolation at the field or watershed scale is difficult. In this study, caesium-137 (137Cs) was used to investigate the spatial extent and severity of soil erosion for an 80-ha watershed in Southeastern Quebec (cultivated area = 75 ha). Soil samples were collected based on a 25 (30 m grid and revealed soil redistribution rates ranging from -20 to +12 Mg ha-1 yr-1. From radiocaesium measurements, it was estimated that the experimental watershed experienced an average loss of 3.0 Mg ha-1 yr-1 with net sediment export of 2.8 Mg ha-1 yr-1 and a sediment delivery ratio of 93%. Snowmelt erosion is believed to have played an important role in the soil redistribution in this small watershed. Changing sampling strategy was tested (50 x 60 m and 100 x 120 m grid rather than 25 x 30 m) and only minor changes were noticed on soil erosion and sediment production estimates, when samples corresponding to the 50 x 60 m grid were used. Key words: Caesium-137 (137Cs), watershed, water erosion, snowmelt erosion, sampling strategy


2019 ◽  
Vol 7 (2) ◽  
pp. 100-111
Author(s):  
Miskar Maini ◽  
Junita Eka Susanti

Standar permintaan engineering pesawat agar desain bangunan infrastruktur di area Air Strip Runway 2600 yang ada dapat mempunyai fungsi lain. Sedangkan kondisi lain sangat menentukan keselamatan karena lahan di sekitar Air Strip Runway 2600 Bandara Depati Amir (PGK) jika tidak ditutupi vegetasi seperti rumput, kondisi lain lahan yang belum ditutupi vegetasi di sekitar Air Strip Runway 2600 berpotensi akan mengalami erosi lahan, kemudian hasil erosi lahan ini akan terbawa oleh aliran air sehingga akan masuk ke saluran drainase yang akan menyebabkan sedimentasi pada saluran drainase tersebut, akhirnya akan berkurang efektifitas kinerja saluran drainase tersebut. Metode yang digunakan untuk memprediksi laju rata-rata erosi di area Air Strip Runway 2600 dengan memperhitungkan faktor erosivitas hujan, erodibilitas tanah, kemiringan lereng atau panjang lereng, pengelolaan tanaman dan konservasi tanah, yang masing masing tata guna lahan tersebut mengacu pada Masterplan Ultimate Bandara Depati Amir (PGK). Perhitungan dilakukan menggunakan persamaan USLE (Universal Soil Loss Equation) yang dikembangkan oleh Wischmeier dan Smith (1965, 1978), kemudian Sediment Delivery Ratio (SDR) dan Sediment Yield.Hasil penelitian ini, prediksi laju erosi permukaan pada area Air Strip Runway 2600 Bandara Depati Amir (PGK) tahun pertama yang mencapai 5,60 mm/tahun atau 100,76 Ton/Ha/tahun, laju erosi tahun kedua mencapai 3,38 mm/tahun atau 60,84 Ton/Ha/tahun dapat diklasifikasikan ke dalam kelas bahaya erosi sedang (kelas III) dan nilai SDR adalah sebesar 56,3%, nilai sediment yield (SR) pada tahun pertama sebesar 5.887,59 Ton/Tahun, pada tahun kedua ketika rumput pada area Air Strip telah tumbuh dengan sempurna terjadi penurunan hasil sediment yield yaitu nilai SR sebesar 3.554,85 Ton/Tahun.


2019 ◽  
Vol 6 (2) ◽  
pp. 47
Author(s):  
Mirza Irwansyah ◽  
Cut Nursaniah ◽  
Laila Qadri

Meureudu Riparian in the past was a place of a collective settlements; it was then developed  to become a Meureudu City in Aceh Province, Indonesia. Initially, it was formed as traditional fishermen settlements but now has shifted into semi-modern settlements. However, the settlements developed sporadically to form an unplanned pattern of settlements. This condition resulted in low maintaining river and non-adaptive existence of the dwellings with the environment. Floods occur repeatedly in the river that affected great lost to the community. This study aimed to propose residential pattern design and adaptive settlements with Meureudu River riparian. Easy access roads to markets will facilitate economy growth to the people. This will also cause large numbers of unbridled migrants to enter and build settlements. In this study the a combination of quantitative methods based on interview data and questionnaires and qualitative exploratory methods based on field observation were used. The data were collected through observation, field measurement and secondary data sources. The results show that the condition of settlements along the river basin do not reflect the culture of the river. In order not to further aggravate the condition of the settlement and its impact on the occupants, we recommended two types of houses, namely in the form of stage and non-stage. The stage houses are located on the riverfront with an orientation overlooking the river. Additionally, undersea area can be used as security from the puddle of river water runoff during the flood and as a garden area and public while dry­­, while at a distance of 100 meters from the river non-stage houses form would be built because the runoff of flood water no longer affects the occupancy.


2018 ◽  
Vol 40 ◽  
pp. 03019
Author(s):  
Dayu Wang ◽  
Chunhong Hu ◽  
Chunming Fang ◽  
Jianzhao Guan ◽  
Lei Zhang

In recent years, the sediment delivery ratio (SDR) of the Three Gorges reservoir (TGR) has noticeably decreased as a result of the increase in water levels at the dam site and the decrease in inflow of fine particles, thereby resulting in increased reservoir siltation. Therefore, it is vital to research the factors that influence the SDR of the TGR. Factors that could have impact on the SDR were studied using TGR monitoring data. The study indicated that the water level at the dam site and inflow and outflow rates could have contributed to the change in the SDR. A sensitivity analysis of the influencing factors was then carried out using a mathematical model to simulate numerous sediment movement scenarios in the TGR. By changing the input conditions of the model, sufficient results were obtained to enable a sensitivity analysis of each factor. The results showed the flood retention time (FRT)—the ratio of reservoir capacity to average outflow discharge—was the principal factor influencing the SDR. The other factors (inflow sediment concentration, inflow sediment coefficient, inflow sediment gradations, and the shape coefficient of the inflow flood shape coefficient), also had an influence on the SDR. However, under different levels of FRT, their degrees of influence on the SDR were not the same..


2019 ◽  
Vol 31 (1) ◽  
pp. 28-38
Author(s):  
LIU Shangwu ◽  
◽  
ZHANG Xiaofeng ◽  
XU Quanxi ◽  
ZHANG Ouyang ◽  
...  

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