scholarly journals Environmental geology assessment on the regional Pitay landfill site: a case study in Kupang, Indonesia

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Adept Titu-Eki ◽  
Herry Z. Kotta
Keyword(s):  
Environmental Degradation ◽  
Rainfall Intensity ◽  
Buffer Zone ◽  
Provincial Government ◽  
Landfill Site ◽  
Geographical Information ◽  
Exclusion Criterion ◽  
Environmental Geology ◽  
Slope Gradient ◽  
Screening Process

AbstractThe Provincial Government of East Nusa Tenggara of Eastern Indonesia has intended to construct a new regional landfill site in Pitay–Kupang, which would accommodate municipal waste of two cities. Considering that environmental degradation in landfill sites has been a substantial issue for many developing cities in Indonesia, this study evaluates the pre-determined site on a local scale based on environmental geology parameters. It employs a conventional Geographical Information System based—Multi-Criteria Decision Analysis (GIS-MCDA) method which is based on the analysis of regional criterion, assessed by expressing values on each parameter presented on thematic maps and overlaid altogether as a screening process, and the exclusion criterion analysis, which sets a buffer zone to filter out irrelevant locations. The regional criterion parameters are: Lithology, groundwater depth, slope gradient and rainfall intensity, whilst the exclusion criterion parameters are: Distance from rivers and lakes, shorelines, settlements, main roads, airports and protected areas, distance from potential geological hazards such as fault zones, floods and mass movements, and distance from any geological potential which may be developed in the future. The biggest area reduction for suitable landfill site candidate is lithology, correlating with groundwater depths, and distance from rivers. Here we identified four potential sites located west and centre of Pitay, situated on Bobonaro scaly clay lithology unit, arguably possessing no groundwater with a slope gradient of 0–20%, rainfall intensity below 1000 mm, and is distant from any potential hazards, promising geological resources and other unfavorable criteria relating to environmental degradation.

Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

2011 ◽  
Vol 347-353 ◽  
pp. 2302-2307 ◽  
Author(s):  
Hong Xiang Wang ◽  
Yi Shi ◽  
Jian Ma ◽  
Cai Yan Lu ◽  
Xin Chen
Keyword(s):  
Point Source ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Inorganic Nitrogen ◽  
Rainfall Amount ◽  
Organic N ◽  
Dissolved Inorganic Nitrogen ◽  
Slope Gradient ◽  
N Loss ◽  
Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

scholarly journals What evidence exists on ecotechnologies for recycling carbon and nutrients from domestic wastewater? A systematic map

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Solveig L. Johannesdottir ◽  
Biljana Macura ◽  
Jennifer McConville ◽  
Dag Lorick ◽  
Neal R. Haddaway ◽  
...  
Keyword(s):  
Domestic Wastewater ◽  
Evidence Base ◽  
Common Type ◽  
Geographical Information ◽  
Treated Wastewater ◽  
Bibliographic Databases ◽  
Nitrogen And Phosphorus ◽  
Systematic Map ◽  
Screening Process ◽  
Recovery And Reuse

Abstract Background Eutrophication of the Baltic Sea, and many other water bodies, is partly the result of point-source emissions of nutrients and carbon from wastewater. At the same time, nitrogen and phosphorus planetary boundaries have been breached. There is a need for more efficient resource management, including the recovery and reuse of nutrients and carbon in waste. The aim of this paper is to collate evidence on ecotechnologies intended for use in the wastewater sector globally to facilitate the recovery or reuse of carbon and/or nutrients. Methods Searches were performed on literature published between 2013 and 2017 and in 5 bibliographic databases, 1 search engine, and 38 specialist websites. Database searches were performed in English. Searches in specialist websites were also performed in Finnish, Polish and Swedish. There was no geographical limitation. Screening was conducted at title and abstract level, and on full texts. Apart from bibliographical information, we extracted information on ecotechnology type, intervention, details of the recovery or reuse, the type of wastewater stream to which the ecotechnology is applied, the study location, type and design. Prior to screening and coding, we conducted consistency checks amongst reviewers. We generated a searchable database of coded studies. Findings were synthesised narratively and visualised in a geographical information system (i.e. an evidence atlas). We identified a series of knowledge gaps and clusters that warrant further research. Results The search resulted in 4024 records, out of which 413 articles were retained after the screening process. In addition, 35 pre-screened studies from the specialist website searches were added. Together, these 448 articles contained 474 individual studies of 28 types of ecotechnologies. A combination of ecotechnologies (16.7%), followed by microalgae cultivation (14.1%) were the most frequent ecotechnologies in the evidence base. Ecotechnologies for recovery composed 72.6% of the evidence base. The most common wastewater streams for recovery were mixed wastewater and sludge (73.8%). There was a relative lack of studies on recovery from source-separated wastewater. The most common type of recovery was energy (27.3%), followed by simultaneous recovery of nitrogen and phosphorus (22.1%). Reuse of recovered substances was described in 22.8% of the studies. The most common type of reuse was of nitrogen and phosphorus (57.4%), followed by joint reuse of organic carbon, nitrogen and phosphorus (35.2%). Reuse ecotechnologies were mostly focused on the use of wastewater for irrigation or reuse of biosolids, and not on the nutrients that had been extracted through e.g. precipitation of struvite. In 22 studies both recovery and reuse were described. In total, 60 different study countries were reported in the evidence base, and the most common study location was China. Conclusions We found substantial evidence for the recovery and reuse of nutrients and carbon from wastewater sources. The relative abundance of studies where substances are recovered compared to studies where they are reused, suggests a knowledge gap on reuse of recovered nutrients and carbon. The majority of studies on reuse were on irrigation with treated wastewater or reuse of biosolids, and not on reuse of extracted nutrients such as struvite.

scholarly journals Hydraulic characteristics of varying slope gradients, rainfall intensities and litter cover on vegetated slopes

2017 ◽  
Vol 49 (2) ◽  
pp. 506-516 ◽  
Author(s):  
Jiamei Sun ◽  
Dengxing Fan ◽  
Xinxiao Yu ◽  
Hanzhi Li
Keyword(s):  
Reynolds Number ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Forest Litter ◽  
Resistance Coefficient ◽  
Litter Layer ◽  
Slope Gradient ◽  
Power Functions ◽  
Yield Rate ◽  
Litter Cover

Abstract Litter produced by forests performs crucial functions in rainfall interception and soil conservation, particularly in the condition that larger raindrops formed by canopy accelerate soil erosion. To explore how forest litter exerts runoff hydrological characteristics and sediment yield processes, experiments on forest covered (Vitexnegundo var. heterophylla) slopes were conducted under various combinations of rainfall intensities and slope gradients. The results showed that litter reduced runoff yield rate by 9–31% and reduced sediment yield rate by 65–90%, with mean runoff and sediment reductions of 18% and 76% for all treatments. On forest covered slopes, Reynolds number and runoff power generally increased with the increase in both rainfall intensity and slope gradient. Litter layer reduced Reynolds number and runoff power with 8–29% and 56–80%, respectively. Darcy–Weisbach resistance coefficient decreased by increasing rainfall intensity and slope gradient. Litter layer increased Darcy–Weisbach resistance coefficient by three to nine times. Relationships between sediment yield rate and Reynolds number, runoff power, Darcy–Weisbach resistance coefficient were described by exponential, linear, power functions, respectively. The critical runoff power values for slopes with and without litter were 0.0027 and 0.0010 m/s, respectively. Reynolds number was the best hydrodynamic parameter for dynamic erosion characterizing.

scholarly journals Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

2016 ◽  
Vol 64 (3) ◽  
pp. 237-245 ◽  
Author(s):  
Feng Qian ◽  
Dongbin Cheng ◽  
Wenfeng Ding ◽  
Jiesheng Huang ◽  
Jingjun Liu
Keyword(s):  
Soil Erosion ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Purple Soil ◽  
Three Gorges ◽  
Slope Gradient ◽  
Stream Power ◽  
Yield Rate ◽  
The Three Gorges ◽  
Subsurface Runoff

Abstract Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20°) were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min-1). The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w), stream power was the best predictor of sediment yield rate (R2 = 0.884). Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R2 = 0.897). The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

Sensitivity analysis of gully sidewall expansion to topography and rainfall factors

2020 ◽  
Author(s):  
Ma Yulei ◽  
Xu Xiangzhou
Keyword(s):  
Correlation Coefficient ◽  
Rainfall Intensity ◽  
Retaining Wall ◽  
Initial Slope ◽  
Slope Gradient ◽  
Land Loss ◽  
Remarkable Change ◽  
Gentle Slope ◽  
Rainfall Duration ◽  
Sensitivity Coefficients

<p>Gully sidewall expansion is an essential process of gully development, and its trigger condition and dynamic process are subject to multifactor effects. This study consisted of 10 sets of experiments, and three factors were considered: three rainfalls (60 mm, 48mm and 24mm), two initial slope gradients (70° and 80°) and two slope heights (1 m and 1.5 m). Then the increase-rate-analysis method was used to evaluate the variations in the changes of slope gradients of sidewall and retreat rates of gully shoulder-line with respect to changes in other causal parameters of rainfall and topography. The results are shown as follows: (1) The area of land loss of the upper gentle slope was positively correlated with the volume of gravity erosion. The correlation coefficient between the volume of gravity erosion and the area of land loss of the upper gentle slope, r<sub>1</sub>, is 0.91. The correlation coefficient between the volume of water erosion and the area of land loss of the upper gentle slope, r<sub>2</sub>, is 0.59. This shows that mass failure was the main cause to induce the land loss of the upper gentle slope in the process of sidewall expansion. (2) The rainfall duration and initial slope gradient had significant influences on the change of slope gradient of landform in the experiments. The sensitivity coefficients of rainfall intensity, rainfall duration, initial slope gradient and slope height for the change of slope gradient of the sidewall were 0.3, 2.2, 1.3 and -0.2, respectively. The increased initial slope gradient and rainfall duration may have caused the increases of the volume and number of gravity erosion, ultimately resulting in a remarkable change of slope gradient of the sidewall. (3) The most significant factor affecting the retreat rate of gully shoulder-line were rainfall intensity and initial slope gradient. The sensitivity coefficients of the rainfall intensity, rainfall duration, initial slope gradient and slope height for the retreat rate of gully shoulder-line were 3.0, 1.5, 3.0 and -0.1. As a result, the retaining wall construction was preferable to control the gully sidewall erosion. The results of this study may be referred for analyzing the mechanism of sidewall expansion and controlling the loess sidewall expansion.</p>

Quantitative Evaluation of the Relationship Between Slope Gradient and Infiltration Capacity Based on a Rainfall Experiment Using Pit Sand

2020 ◽  
Vol 15 (6) ◽  
pp. 745-753
Author(s):  
Toru Danjo ◽  
◽  
Tomohiro Ishizawa
Keyword(s):  
Surface Layer ◽  
Slope Stability ◽  
Soil Loss ◽  
Rainfall Intensity ◽  
Horizontal Distance ◽  
Slope Gradient ◽  
Slope Surface ◽  
Infiltration Capacity ◽  
Tank Model ◽  
The Relationship

The infiltration of rainfall into a slope surface may affect slope stability; thus, it is important to understand the amount of rainfall infiltration (hereafter referred to as the “infiltration capacity”) for a slope surface layer when evaluating slope stability. This research focuses on slope gradient, a factor affecting the infiltration capacity, and performs two types of water-spraying experiments using pit sand under the same conditions but with different slope gradients. In the first experiment, the surface flow rate and soil loss were measured using an earth-tank model with a horizontal distance of 0.5 m, depth of 0.1 m, and width of 0.2 m to form slope gradients of 2°, 20°, and 40° to clarify the effect of slope gradient on the infiltration capacity. In the second experiment, a water-spraying experiment that closely simulated natural rainfall was performed at a large-scale rainfall facility owned by the National Research Institute for Earth Science and Disaster Resilience (NIED), Japan. This experiment used an earth-tank model with a horizontal distance of 1.21 m, depth of 0.5 m, and width of 0.5 m to form slope gradients of 2°, 10°, 20°, 30°, and 40° with the aim of proposing a quantitative evaluation method for the relationship between the slope gradient and infiltration capacity. The results showed that the soil loss and infiltration capacity increased as the slope gradient increased in the case of the pit sand used in the experiments. This was confirmed to be due to the fact that an increased gradient allowed grains with diameters of <50 μm in the slope surface layer to flow out easily, thereby increasing the infiltration capacity. In addition, the relationship between the rainfall intensity and infiltration capacity revealed that the infiltration capacity varied depending on the rainfall intensity and slope gradient, which is unlike the relationship for constant values such as the permeability coefficient. Moreover, the research findings indicated a strong, positive linear relationship (R2 = 0.98) between the slope gradient and fitting factor Ic. Therefore, the relationship between rainfall intensity and the infiltration capacity could be expressed using the fitting factor Ic. This suggests the possibility of quantitatively evaluating the relationships between rainfall intensity, the infiltration slope gradient, and the infiltration capacity.

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