Application of Geographic Information Systems and Sediment Routing Methods in Sediment Mapping in Krueng Jreu Sub-Watershed, Aceh Province, Indonesia

Land management in the Krueng Jreu sub-watershed (Aceh Province, Indonesia) that did not follow soil and water conservation methods encouraged erosion. This can lead to silting of rivers or irrigation canals due to sediment deposition. Limited tools were the main reason for the infrequent measurement and mapping of these sediments in watersheds. Therefore, this study aims to conduct sedimentary mapping using GIS techniques combined with the sediment routing method to successfully produce a map of sediment assessment criteria for the Krueng Jreu sub-watershed area from 2010 to 2019. Rainfall and spatial data from the Krueng Jreu sub-watershed were analyzed to obtain several parameters of surface runoff, peak discharge, erodibility, slope, the value of ground cover, and land management. The results show that the Krueng Jreu sub-watershed was included in the wet climate type. The type of land use classification of savanna accounted for the most significant runoff, and land use type of open soil gave the smallest runoff. The maximum erosion found in the secondary dryland forest type land classification. It was known that the type of secondary dryland forest land use was the most significant contributor to sediment occurrence in the Krueng Jreu sub-watershed area.

Which environmental factors control extreme thermal events in rivers? A multi-scale approach (Wallonia, Belgium)

Managers need to know how to mitigate rising stream water temperature (WT) due to climate change. This requires identifying the environmental drivers that influence thermal regime and determining the spatial area where interventions are most effective. We hypothesized that (i) extreme thermal events can be influenced by a set of environmental factors that reduce thermal sensitivity and (ii) the role played by those factors varies spatially. To test these hypotheses, we (i) determined which of the environmental variables reported to be the most influential affected WT and (ii)identified the spatial scales over which those environmental variables influenced WT. To this end, the influence of multi-scale environmental variables, namely land cover, topography (channel slope, elevation), hydromorphology (channel sinuosity, water level, watershed area, baseflow index) and shade conditions, was analyzed on the three model variables (day thermal sensitivity, night thermal sensitivity, and non-convective thermal flux) in the model developed by Georges et al. (2021) of the temporal thermal dynamics of daily maximum WT during extreme events. Values were calculated on six spatial scales (the entire upstream catchment and the associated 1 km and 2 km circular buffer, and 50 m wide corridors on each side of the stream with the associated 1 km and 2 km circular buffer). The period considered was 17 extreme days during the summer identified by Georges et al. (2021) based on WT data measured every 10 min for 7 years (2012–2018) at 92 measurement sites. Sites were located evenly throughout the Wallonia (southern Belgium) hydrological network. Results showed that shade, baseflow index (a proxy of the influence of groundwater), water level and watershed area were the most significant variables influencing thermal sensitivity. Since managers with finite financial and human resources can act on only a few environmental variables, we advocate restoring and preserving the vegetation cover that limits solar radiation on the watercourse as a cost-effective solution to reduce thermal sensitivity. Moreover, management at small spatial scale (50 m riparian buffer) should be strategically promoted (for finance and staffing) as our results show that a larger management scale is not more effective in reducing thermal sensitivity to extreme events.

Ethnozoological study of the wild pig (Sus spp.) hunting among Sundanese in Upper Citarum Watershed area, West Java, Indonesia

Mulyanto D, Abdoellah OS, Iskandar J, Gunawan B. 2021. Ethnozoological study of the wild pig (Sus spp.) hunting among Sundanese in Upper Citarum Watershed area, West Java, Indonesia. Biodiversitas 22: 4930-4939. In the past, wild pigs had a high population in the rural ecosystem of West Java. However, the population of wild pigs, particularly Javan warty pig, decreases due to forest destructions and intensive hunting. This study aimed to elucidate the local knowledge on wild pigs, the mode of hunting, and diverse aspects of wild pig hunting. We conducted qualitative methods with ethnozoological approach, including participant observation and in-depth interview. The results showed that based on the local people the wild pig can be divided into four “races”, while based on zoology, two species of wild pig are documented in Java. During hunts all members get specific key roles. Thus, hunting success is increased by division of labor. Hunting wild pigs played an important role in socio-economic and cultural function for the village community. Due to intensive hunting of wild pigs, the population of these animals, particularly the Javan warty pig are decreased, and consequently the socio-economy of this animal in rural ecosystem may decrease ot even disappear.

The effect of land-use change on river watershed quality (case study: Cimahi Watershed, West Java, Indonesia)

Increasing population growth is one of the impacts of the growth of a city or district in an area. This also happened in the Cimahi watershed area. As the population grows, so does the need for land which increases the land-use change in the Cimahi watershed. Land-use changes will affect the surrounding environment and one of them is the river, especially river water quality. As a watershed area, there is one main river that is the source of life as well as the Cimahi watershed, whose main river is the Cimahi River. The purpose of this study was calculated the relationship between land-use change in the Cimahi watershed and the water quality parameters of the Cimahi River. The correlation between the two was calculated using Pearson correlation. Water quality parameters can be seen based on BOD and DO values. BOD and DO values are the opposite because good water quality has high DO values and low BOD values. The correlation between land-use change and BOD was 0.328 is in the area of settlements area. In contrast, to DO values, an increase in settlements/industrial zones will further reduce DO values so that both have a negative correlation, which is indicated by a value of -0,535. The correlation between settlements with pH and temperature values is 0.664 and 0.812. While the correlation between settlements with TSS and TDS values are 0.333 and 0.529, respectively. In this study, it can be seen that there is a relationship between the decline in water quality and changes in land use.

Analysis of flood vulnerability in the lawo watershed Soppeng Regency

The Lawo Watershed (DAS) is a watershed located in Soppeng Regency and every year during the rainy season it is prone to flooding. Other factors that cause flood vulnerability are slope, rainfall, soil type, altitude, and inappropriate land use. This study aims to determine the distribution of the level of flood vulnerability in the Lawo watershed, Soppeng Regency. The type of research used is descriptive quantitative. The method of making maps uses overlays and scoring between variables. Each variable will be given a score by giving weights and values according to the classification. Variables that have gone through the scoring stage will be overlaid with other variables using the ArcGIS application so as to produce a map of the level of flood vulnerability. The data analysis technique used descriptive method. The result of the research is a map of the level of flood susceptibility with four levels of vulnerability. There are two dominant levels of flood vulnerability in the Lawo watershed, namely not prone to flooding and prone to flooding. The flood-prone level is located downstream of the Lawo watershed with an area of 13,172 ha or 34.33% of the total watershed area, while the non-flood prone level is located in the upstream part of the watershed with an area of 13,923 ha or 36.28% of the total watershed area. The dominant factor that causes flooding in the Lawo watershed is the slope and land use. Most of the area of the Lawo watershed has a slope of 0-8% with a presentation of 57.22% of the total watershed area, and 32.97% of land use is in the form of rice fields and swamp shrubs.

Impact of Watershed on Cost and Returns Structure of Soyabean Cultivation in Nek Region

Land is a scarce resource and basic unit for any material production. It can support the needs of the growing population, provided they use land in a rational and judicious manner. The biggest crisis that the world is facing in the 21st century is the crisis of water. Looming water scarcity over large parts of the world and increased withdrawal by agriculture from 2500 km3 in 2000 to 3200 km3 by 2025 has attracted the attention of policy makers and researchers for achieving food and water security. Soybean (Glycine max) was one of the major Kharif crop cultivated in watershed (71.50 acres) and non-watershed areas (80.35 acres). Hence, an attempt was made to study the impact of watershed on the cost and returns structure in soybean cultivation in selected four districts of NEK region with the sample size of 240. It was observed inputs utilized for the cultivation in watershed areas was higher than non-watershed areas. Due to higher input utilization the total cost in watershed (Rs. 17080.90/ha.) was higher than non-watershed (Rs. 14257.62/ha.). The returns were also higher in watershed area (Rs. 27941.76/ha.). The returns per rupee of investment realized in watershed areas was 1.64 which is slightly higher than (1.56) non-watershed areas. The higher returns per rupee of investment indicating soyabean cultivation in the watershed area was financially feasible.

The role of soil, water and forest conservation on vegetation cover and landscape greenness in degraded areas of upper Blue Nile

Recently, large-scale soil, water, and forest conservation/protection practices have been implemented in Ethiopia. This study aimed to evaluate the impact of soil, water, and forest conservation/protection on vegetation cover and landscape greenness in the Gumara watershed. Landsat satellite imageries were used to analyze the changes using land use/cover and net difference vegetation index (NDVI) and its differencing methods. Over the period 1995-2017, forestland and shrub-woodland covers increased by 48.4% (2.8-4.2%) and 8.3% (20.2-21.9%), respectively. Similarly, the NDVI result showed high improvements in landscape greenness and vegetation density. A 13.5% of the watershed area experienced a significant increase, of which 61.4% was observed on forest and shrub-woodland covers. The watershed area covered by very high (NDVI>0.4) and high (NDVI 0.3-0.4) vegetation density classes were increased by 189.2 and 145.5%, respectively. Upon the increasing human pressure and related problems, the observed improvement of vegetation cover and landscape greenness show the positive impact of soil, water, and forest conservation/protection practices done for the last two decades. Therefore, strengthening the current efforts and investing more in sustainable and evidence/priority-based soil, water, and forest conservation measures that are ecologically friendly with diversified livelihood importance can bring a more effective result of land rehabilitation.

P14.30 Voxelwise analysis of spatial distribution of postoperative ischemia in diffuse glioma

BACKGROUND Surgical treatment of diffuse glioma is performed to reduce tumor mass effect and to pave the way for adjuvant (chemo)radiotherapy. As a complication of surgery, ischemic lesions are often found in the postoperative setting. Not only can these lesion induce neurological deficits, but their volume has also been associated with reduced survival time. Prior studies suggest areas with a singular vascular supply to be more prone to postoperative ischemic lesions, although the precise cause is yet unknown. The aim of this study was to explore the volumetric and spatial distributions of postoperative ischemic lesions and their relation to arterial territories in glioma patients. MATERIAL AND METHODS We accessed a retrospective database of 144 adult cases with WHO grade II-IV supratentorial gliomas, who received surgery and postoperative MRI within 3 days in 2012–2014. We identified 93 patients with postoperative ischemia, defined as new confluent diffusion restriction on DWI. Ischemic lesions were manually delineated and spatially normalized to stereotaxic MNI space. Voxel-based analysis (VBA) was performed to compare presence and absence of postoperative ischemia. False positive results were eliminated by family-wise error correction. Areas of ischemia were labeled using an arterial territory map, the Harvard-Oxford cortical and subcortical atlases and the XTRACT white matter atlas. RESULTS Median volume of confluent ischemia was 3.52cc (IQR 2.15–5.94). 23 cases had only ischemic lesion in the left hemisphere, 46 in the right hemisphere and 24 bilateral. Median volume was 3.08cc (IQR 1.35–5.72) in left-sided lesions and 2.47cc (1.01–4.24) in right-sided lesions. Volume of ischemic lesions was not associated with survival after 1, 2 or 5 years. A cluster of 125.18cc was found to be significantly associated with development of postoperative ischemia. 73% of this cluster was situated in the arterial territory of the right middle cerebral artery (MCA), limited by the border of the posterior cerebral artery (PCA), and the watershed area between the right MCA and the right anterior cerebral artery (ACA). Significant areas were located in the frontal lobes, spanning into the right temporo-occipital region, and predominantly included right and left thalamus, caudate nucleus, putamen, pallidum, as well as right temporal gyri and insular cortex, and parts of the right corticospinal tract, longitudinal fasciculi and superior thalamic radiation. CONCLUSION We found slightly more and larger ischemic lesions in the right than left hemisphere after glioma resection. A statistically significant cluster of voxels of postoperative ischemia was found in the territory of the right MCA and watershed area of the right ACA. Exploration of the spatial distribution of these lesions could help elucidate their etiology and form the basis for predicting clinically relevant postoperative ischemia.