Basin Land Use Research Articles

Exploring new methods for assessing landscape ecological risk in key basin

Scientific assessment of landscape ecological risk (LER) aims to optimize land use patterns and mitigate regional ecological hazards. However, accurate LER assessment requires the selection of a feasible spatial analysis scale. This study identified the optimal spatial scale by analyzing high-resolution data from 2006, 2012, and 2019. Within the “production-living-ecological” spatial (PLES) perspective, this study employed six methods to depict the pattern changes and spatiotemporal variations of LER. These included the Markov transfer matrix model, the geoscience information atlas–gravity center model (GIAGC), the LER index model, Min/Max Autocorrelation Factors, the Sequential Gaan simulation (MAF-SGS) multivariate geostatistical model, and spatial autocorrelation. The results are as follows: 1) A granularity of 10 m and a magnitude of 200 m are the most effective parameters for LER assessment. 2) From 2006 to 2019, there was a shift in the structure of the landscape pattern from “ecological space” to “productive space”, accompanied by a tendency for the center of gravity to shift towards the southwest. 3) The non-structural spatial factors contributing to LER are gradually increasing, and the maximum variability is steadily rising. Medium-low risk areas dominate the basin, and the spatial distribution of LER exhibits an overall pattern: high in the center, low in the southwest, and low in the northwest. Specifically, a low-low spatial clustering pattern is predominant; however, there is a general upward trend in LER. In summary, this study provides a scientific basis for adjusting basin land use structures, resolving ecological risks, and promoting high-quality sustainable development.

Comparative deterministic and probabilistic approaches for assessing the aquatic ecological risk of pesticides in a mixed land use basin: A case study in Uruguay

Environmental concentrations of 25 pesticides in superficial water were employed to conduct an ecological risk assessment (ERA) in a mixed land-use basin utilized as a drinking water source. A deterministic risk assessment (RQ) was utilized to evaluate the chronic risk to aquatic biota, while a probabilistic risk assessment (PRA) approach was applied to assess the acute and chronic risk in the most sensitive species and at the community level. A high risk was identified for insecticides (pyrethroids, organophosphates and organochlorines). RQs ranged from 4.0e−4 (2,4-D) to 105.3 (ethion) considering median concentrations and from 8.0e−4 (2,4-D) to 230 (p,p’-DDT) considering extreme concentrations. Temporal variation in ΣRQs showed the highest risk during spring and summer months, which is related to the crop calendar and land use in the Laguna del Cisne basin. For PRA, the probability of exceeding the hazardous concentration HC5 (5th percentile) was higher for the most sensitive species in chronic exposure, especially for cypermethrin (38.9 %), permethrin (25.6 %), and chlorpyrifos (16.6 %). In the case of acute exposures, the probability of surpassing HC5 was higher for the entire freshwater biota, with the highest values observed for bifenthrin (28.3 %), cypermethrin (25.5 %), permethrin (11.75 %), and ethion (11.1 %). The advantages and disadvantages of PRA for assessing pesticide ecological risk were compared with the conventional deterministic RQs approach, highlighting that PRA offers improvements over the deterministic risk assessment, especially for organophosphate pesticides. Additionally, PRA provides a more comprehensive evaluation of risk for both short and long-term exposure, has the potential to incorporate others available toxicity data (e.g., LD50, Daily Intake), and utilizes different hazardous concentrations, such as HC5, HC10, and HC50. Our findings emphasize the urgent need to establish a national regulatory framework to evaluate and mitigate pesticide risks in aquatic ecosystems, especially in drinking water source like Laguna del Cisne.

Assessing Land Use Dynamics of Lower Bhavani Basin Using Multiple GIS Platforms

Land use describes the actual form of land, such as a forest or open water and classification based on human utilization. Land use map provides the information about the current landscape of an area. In this study, the Lower Bhavani basin's land use and land cover were classified using GIS platforms and data from the Landsat 8 satellite. The platform utilized in this study were Semi-Automated Plugin (SAP) in QGIS and Random forest method in Google Earth Engine (GEE). The findings suggested that both platforms performed efficiently and displayed comparable percentages of land covered by various land use features. The accuracy of the resulting land use map was evaluated using a Google Earth image, and it was discovered that SAP and GEE hold 91.8% and 92.6% of the total accuracy. This study aids in evaluating and classifying the various Geographic Information System platforms land use trends.

Composition and Flux of Dissolved and Particulate Carbon and Nitrogen in the Lower Tocantins River

AbstractThe Tocantins River contributes ∼5% of the total flux of water to the Amazon River plume in the Atlantic Ocean. Here, we evaluate monthly variability in the composition and abundance of carbon, nitrogen, and suspended sediment in the lower reaches of the Tocantins River from 2014 to 2016. Dissolved organic carbon concentrations generally increased during periods of high discharge and are ∼1.5 times lower than average concentrations at the mouth of the Amazon River. Dissolved inorganic carbon similarly increased during periods of high discharge. Total dissolved nitrogen and individual nitrogen species followed a similar temporal pattern, increasing during high water. predominated the dissolved inorganic nitrogen pool, followed by , and , characteristic of environments with a relatively low anthropogenic impact. Dissolved fractions represented 92% of the total carbon exported and 78% of the total nitrogen exported. The suspended particulate sediment flux was 2.72 × 106 t yr−1, with fine suspended sediment dominating (71.3%). Concentrations of carbon relative to nitrogen indicate a primarily terrigenous source of organic matter and CO2 derived from in situ respiration of this material during the rainy season and a primarily algal/bacterial source of organic matter during the dry season. Considering past estimates of dissolved carbon and nitrogen fluxes from the Amazon River to the Atlantic Ocean, the Tocantins River contributes 3% and 3.7% to total fluxes to the Amazon River plume region, respectively. While this contribution is relatively small, it may be influenced by future changes to the basin's land use and hydrology.

Land-use changes in Amazon and Atlantic rainforests modify organic matter and black carbon compositions transported from land to the coastal ocean

This study assessed black carbon (BC) dynamics, concentrations, and the organic matter (OM) isotopic carbon composition in northeastern South America drainage basin coastal sediments. Paraíba do Sul (PSR; Atlantic Rainforest, Brazil) coastal sediments displayed more 13C-enriched values (−22.6 ± 1.3 ‰ [n = 13]) than Amazon and Sinnamary (Amazon Rainforest in French Guiana and Brazil) sediments (−25.0 ± 3.1 ‰ [n = 14] and − 26.1 ± 1.0 ‰ [n = 6], respectively), indicating that local land-use basin changes have altered the OM composition, i.e., from natural C3 plant to C4 plants contributions. BC contents normalized to total organic carbon (TOC) content were 0.32 ± 0.24 (n = 8), 0.73 ± 0.67 (n = 6), and 0.95 ± 0.74 (n = 13) mg g−1 TOC for Amazon, Sinnamary and PSR samples, respectively, with BC sources appearing to differ according to different drainage basin vegetation covers. With increasing distance from the river mouths, BC contents exhibited different trends between the coastal zones, with values increasing for the PSR and decreasing values for the Amazon samples. BC distribution in Sinnamary coastal sediments did not display specific patterns. Regarding the Amazon coastal zone, BC contents decreased while the B6CA:B5CA ratios did not show a pattern, which could indicate that BC in the area originates from river transport (aged BC) and that the hydrophobic component of dissolved BC is removed. The BC content mostly increased in the PSR coastal zone, while the B6CA:B5CA ratios were not altered for the entire gradient, indicating the BC stability and possible atmospheric deposition of soot. Our findings indicate that different sources, transformation processes, and hydrological conditions affect BC contents within coastal zones. Continuous land cover changes in both the Amazon and Atlantic Rainforests may result in large-scale marine carbon cycling impacts.

Zoning Strategy for Basin Land Use Optimization for Reducing Nitrogen and Phosphorus Pollution in Guizhou Karst Watershed

Eutrophication caused by excessive total nitrogen (TN) and total phosphorus (TP) emissions is of wide concern for society at large. Studies have revealed certain relationships among land use, TN, and TP. However, the relationships among land use compound topographic position, TP, and TN have seldom been studied. Therefore, the objectives of this paper are to construct optimal zoning of land use and reduce the nutrient load of lakes. Spearman correlation and redundancy analyses were used to reveal the relationship between land use comprehensive topographic position and TN and TP in the lakes of Guizhou Plateau. The results show that the nutritional state of the research area is medium. The trophic level index (TLI) value and TN concentration were high during flood periods, while TP concentration was high in dry periods. The TN concentration in the tributaries was higher than that in the reservoir area. Construction land and valley were the sources of the pollution, whereas forest land and gentle slope were the sink. According to the ”source–sink” effect, once the optimal zoning of land use is completed, the governance of urban land pollution governed areas should be strengthened next. This paper can provide decision support for water environment management and sustainable development decision-making.

Effects of Land Use Change on Rainfall Erosion in Luojiang River Basin, China

This paper, based on daily rainfall erosivity model, ArcGIS, trend analysis and Kriging interpolation method, analyzed the spatial and temporal distribution characteristics of rainfall erosivity in the Luojiang River Basin of China, and then explored the influence relationship between land use change types and rainfall erosivity potential. The results showed the following: (1) from 1980 to 2019, the distribution range of multi-annual rainfall erosivity in the Luojiang River Basin was 14,674–15,227 MJ·mm/ (hm2·h), with an average value of 14,102 MJ·mm/(hm2·h), showing an overall increasing trend; (2) the spatial distribution of rainfall erosivity value tends to be consistent with the multi-year average rainfall, showing a decreasing trend from the middle to the periphery of the basin; (3) land use change is an important factor affecting the spatial and temporal distribution characteristic of rainfall erosivity value in the basin. The increase in rainfall erosivity will undoubtedly increase the potential of soil erosion. This study can provide theoretical reference for future basin land use planning and put forward preventive suggestions according to the distribution characteristics of rainfall erosivity.

Integrating the Budyko framework with the emerging hot spot analysis in local land use planning for regulating surface evapotranspiration ratio

Land use planning regulates surface hydrological processes by adjusting land properties with varied evapotranspiration ratios. However, a dearth of empirical spatial information hampers the regulation of place-specific hydrological processes. Therefore, this study proposed a Local Land Use Planning framework for EvapoTranspiration Ratio regulations (ETR-LLUP), which was tested for the developments of spatially-varied land use strategies in the Dongjiang River Basin (DRB) in Southern China. With the first attempt at integrating the Emerging Hot Spots Analysis (EHSA) with the Budyko framework, the spatiotemporal trends of evapotranspiration ratios based on evaporative index and dryness index, from 1992 to 2018, were illustrated. Then, representative land-cover types in each sub-basin were defined using Geographically Weighted Principal Component Analysis, in two wet years (1998 and 2016) and three dry years (2004, 2009, and 2018), which in turn were identified using the Standard Precipitation Index. Finally, Geographically Weighted Regressions (GWRs) were used to detect spatially-varied relationships between land-cover proportions and evaporative index in both dry and wet climates. Results showed that the DRB was consistently a water-limited region from 1992 to 2018, and the situation was getting worse. We also identified the upper DRB as hotspots for hydrological management. Forests and croplands experienced increasingly water stress compared to other vegetation types. More importantly, the spatial results of GWR models enabled us to adjust basin land use by 1) expanding and contracting a combination of ‘mosaic natural vegetation’ and ‘broadleaved deciduous trees’ in the western and eastern parts of the basin, respectively; and 2) increasing ‘broadleaved evergreen trees’ in the upstream parts of the basin. These spatially-varied land use strategies based on the ETR-LLUP framework allow for place-specific hydrological management during both dry and wet climates.

Land Use and Land Cover Change Detection in the Bhavani Basin of India through Remote Sensing Approach

Using remote sensing data to detect changes in land use and land cover (LULC) is a valuable source of information for various decision support systems. Land use and land cover identification data was used to analyse land conservation, sustainable development, and water resource management. This research aims to determine how the Bhavani basin land use and land cover have changed over the period of time. Land cover changes were detected using Landsat Thematic Mapper (TM) 30 m resolution images in the GIS environment and with image processing techniques for the four years 1999, 2007, 2014, and 2020. The differences in the landuse and land cover classes are described using ERDAS imagine version 2015 and ARC GIS software. The four land cover classes viz. water body, built-up land, barren land, and vegetation were used to classify the region. The accuracy evaluation was assessed separately using the kappa coefficient after carefully examining the image pre-processing and classification. The overall accuracy in the basin was found to be 83.23%, 86.45%, 85.83%, and 88.75 % with a kappa coefficient of 0.79, 0.81, 0.87, 0.85 for the years 1999, 2007, 2014, and 2020 respectively. The Bhavani basin is mostly covered by barren and vegetation. According to the findings, the basin's built-up area has risen by 1.5 percentage to 3.5 percentage in the last 20 years. The increase in the vegetation area and reduction in the barren area may lead to low soil erosion.

Research on Relationship of Total Nitrogen Concentration and Runoff in the Xiangxi River Basin

The response relationship between pollutant and flow rate is very important and is one of the key factors for the reasonable simulation of the model for a basin. The basin land use type, soil types, weather, vegetation distribution, soil and water loss situation are taken as the influence factors to explore its concentration change in migration of pollutants in relation with the response of the flow in Xiangxi River watershed. Emphasis was put on the effects of nitrogen pollutants based on the mass conservation equation combined with the total nitrogen concentration of pollutants. Relationship between total nitrogen pollutants and flow of three types of response relation is preliminary established. Measured data of total nitrogen from 2014 to 2017 are used for verification and error analysis. Results show that the power function is the best relationship, while the logarithm function is the second one, and the exponential function is the third one through trend coincidence, fluctuation range and error analysis. This study is helpful to understand the response relationship between pollutant concentration and discharge in small watershed, so it can also be used for pollutant prediction in small watershed without measured data.

Ecological risk assessment of current-use pesticides and biocides in soils, sediments and surface water of a mixed land-use basin of the Pampas region, Argentina

The present study aimed to assess the ecological risk of 30 current-use agricultural pesticides and biocides in the soil, sediments and aquatic organisms of a mixed land-use basin located in the Depressed Pampas Region of Argentina. Risk Quotients (RQs) were used to evaluate the chronic risk in soil and aquatic organisms, while Toxic Units (TUs) were used to assess the acute risk in sediment-dwelling organisms and aquatic biota. Acetochlor, hydroxy-atrazine, glyphosate, AMPA, metolachlor, imidacloprid and tebuconazole were the only pesticide residues detected (>30%) and quantified in all the matrices evaluated. Glyphosate and AMPA showed the highest concentrations, being their mean and maximum levels 27.90–176.00 μg kg−1 and 270–712.50 μg kg−1 in soils, 8.28–32.0 μg kg−1 and 6.85–17.50 μg kg−1 in sediments, and 1.88–4.36 μg L−1 and 0.66–1.03 μg L−1 in surface water. The RQs in soils showed high chronic risk, mainly due to AMPA and imidacloprid. The TUs in sediments showed acute risk in dwelling organisms, mainly due to glyphosate and imidacloprid. RQs assessment showed a range of chronic risk levels according to the site/sampling event, with higher contribution of atrazine and its metabolites, and acetochlor, whereas TUs assessment showed no acute risk in aquatic biota. In contrast to Europe, in Argentina, there are no restrictions regarding the use of atrazine, acetochlor, imidacloprid and glyphosate to protect aquatic life. Thus, it is recommended that the current Argentine pesticide regulations should be modified to prevent ecological risk and protect ecosystems.

Environmental fragility analysis in reservoir drainage basin land use planning: A Brazilian basin case study

Reservoirs constructed for multiple water and land use changes alter the hydro-sedimentological dynamics of drainage basins, intensifying erosion and silting of water bodies. To ensure water and soil conservation, environmental fragility analysis is a notable tool in land use planning. Potential environmental fragility (PEF) is the dynamic equilibrium of the environment, understood as the natural susceptibility of physical parameters to erosion. In conjunction with the socioeconomic parameter of land use, it generates emergent environmental fragility (EEF). This study analyzes PEF and EEF of the Lobo Reservoir Drainage Basin, a small basin in southeastern Brazil, and recommends environmental zoning derived from its assessment. Physical parameters, on a 1:50,000 scale, and land use spatial data were used to create PEF and EEF maps, followed by recommendations for suitable use for the basin’s sectors, taking into account their environmental fragility and current land use. The results indicate that the basin is primarily classified as medium EEF, which is related to its medium PEF and to the region’s agricultural activities. The proposed environmental zoning designates nearly half the basin as suitable for anthropic use, while 28.5 % is considered a priority for environmental conservation. Areas identified as a priority for conservation/restoration represent some 16 % of the basin. Limitations and potential enhancements to the study’s methodology were encountered, but none impaired the EEF analysis, which identified areas that could favor erosion. The land use planning proposed by the study based on its environmental fragility analysis provides a low cost, flexible, and easy to use method, facilitating its adoption by public managers and use by government technicians. Moreover, the study’s methodology can be widely replicated in other regions and fine tuned in accord with their specific characteristics and morphodynamic patterns.

Use of Artificial Neural Networks and Multiple Linear Regression Model for the Prediction of Dissolved Oxygen in Rivers: Case Study of Hydrographic Basin of River Nyando, Kenya

The process of predicting water quality over a catchment area is complex due to the inherently nonlinear interactions between the water quality parameters and their temporal and spatial variability. The empirical, conceptual, and physical distributed models for the simulation of hydrological interactions may not adequately represent the nonlinear dynamics in the process of water quality prediction, especially in watersheds with scarce water quality monitoring networks. To overcome the lack of data in water quality monitoring and prediction, this paper presents an approach based on the feedforward neural network (FNN) model for the simulation and prediction of dissolved oxygen (DO) in the Nyando River basin in Kenya. To understand the influence of the contributing factors to the DO variations, the model considered the inputs from the available water quality parameters (WQPs) including discharge, electrical conductivity (EC), pH, turbidity, temperature, total phosphates (TPs), and total nitrates (TNs) as the basin land-use and land-cover (LULC) percentages. The performance of the FNN model is compared with the multiple linear regression (MLR) model. For both FNN and MLR models, the use of the eight water quality parameters yielded the best DO prediction results with respective Pearson correlation coefficient R values of 0.8546 and 0.6199. In the model optimization, EC, TP, TN, pH, and temperature were most significant contributing water quality parameters with 85.5% in DO prediction. For both models, LULC gave the best results with successful prediction of DO at nearly 98% degree of accuracy, with the combination of LULC and the water quality parameters presenting the same degree of accuracy for both FNN and MLR models.

Impact of land use and land cover change on water quality: a study of Fuxian Lake

Water quality and basin ecological environment are seriously threatened by development around the lake. The thesis intends to assess basin land use and land cover changes impact on water quality in Fuxian Lake. To achieve this purpose, six periods Landsat images from 1990 to 2016 were used. By using remote sensing and GIS software, the five images were classified into six land use classes. The water quality information was obtained by investigation and collection. Correlation coefficient between LUCC and water quality was celebrated based on SPSS software. The results revealed that, the study area underwent an increase in construction land and farm land with the region development; but forest land and grassland are gradually reduced. In addition, potassium permanganate index is gradually increased. Furthermore, total nitrogen is significantly positively correlated with farmland and construction land, negatively correlated with forest land and grass land. In the final part of the thesis, it is believed that a series land use and land cover changes has happened due to development of Lake Basin, which poses a serious threat to water quality.

Capacity Building in the Congo Basin: Rich Resources Requiring Sustainable Development

The Congo Basin is a unique freshwater ecosystem supporting hundreds of millions of people and a crucial part of regulating Earth’s water cycle. Increasing international attention on its resource potential brings worrying pressures to this understudied region. Equitable collaboration is the key to understanding this complex, interconnected system and enabling its sustainable development.

Changes in Land Use in the Lombok River Basin and Their Impacts on River Basin Management Sustainability

Sustainable management in water resources development strategies depends on the knowledge of phenomena of changes in land use in the river basin as a significant tool in understanding the interactions of environment and human activities. Changes that occur within a certain period on the land cover or land use impacts the basin characteristics, which will ultimately affect river basin management. This paper studies the change of land use in the Lombok river basin in Indonesia based on the Moderate Resolution Imaging Spectroradiometer (MODIS) land use/land cover data version 6 from the years of 2001, 2010, and 2016 which were derived using MODIS Terra and Aqua reflectance supervised classification data. Land use data was then classified into fifteen land use categories according to SWAT classification. QGIS and MapWindow software were applied to analyse the features of land use in the study area, and the SWAT simulation model was applied to simulate the impacts of changing land use in the sub-basin. The study concludes that areas with occurrences of changes in land use impacted the river runoff in the sub-basin. Analysis of river basin land use, when combined with simulation in water resources management, will contribute to optimal and sustainable river basin planning.

LUCC impact on water quality change in Xingyun Lake basin

Basin ecological environment and water quality are seriously threatened by development around the lake. The thesis intends to assess basin Land Use and land Cover Changes (here after abbreviated as LUCC) impact on water quality change in Xingyun Lake basin. To achieve this purpose, land use information was interpreted from six periods high-resolution images in the past 30 years, which were classified into seven land use types. The water quality data was obtained by investigation and collection. SPSS software was used to celebrate the correlation coefficient between water quality and LUCC. The results revealed that, in the study area construction land, transportation land and farm land were underwent an increase with the region development; grassland and bare land were gradually reduced, forest land had become fragmented. In addition, the water pollution index gradually increased since 2000, the water deteriorated significantly. Furthermore, there was a strong positive correlation between water pollution indicator and farmland, construction land and transportation land, which indicated that the deterioration of water quality may be the result of the combined effects of agriculture non-point source pollution, domestic and industrial pollution; there was a significant negative correlation between water pollution indicator and grassland and bare land, which indicated that permeable underlying mat had significant interception and absorption effects on pollutants.

Runoff Modeling of a Coastal Basin to Assess Variations in Response to Shifting Climate and Land Use: Implications for Managed Recharge

We quantified the distribution of hillslope runoff under different climate and land-use conditions in a coastal, mixed land-use basin, the Pajaro Valley Drainage Basin (PVDB), California, USA, in order to evaluate opportunities to improve groundwater supply. We developed dry, normal, and wet climate scenarios using high-resolution historic data and compared contemporary land use to pre-development land use under the different climate scenarios. Relative to pre-development conditions, urban and agricultural development resulted in more than twice as much simulated runoff generation, greater spatial variability in runoff, and less water available for recharge; these differences were most pronounced during the dry climate scenario. Runoff results were considered in terms of potential to support distributed stormwater collection linked to managed aquifer recharge (DSC-MAR), which routes excess hillslope runoff to sites where it can infiltrate and enhance groundwater recharge. In the PVDB, 10% of the annual groundwater deficit could be addressed by recharging 4.3% of basin-wide hillslope runoff generated during the normal scenario, and 10.0% and 1.5% of runoff during the dry and wet scenarios, respectively. Runoff simulation results were combined with an independent recharge suitability mapping analysis, showing that DSC-MAR could be effective in many parts of the PVDB under a range of climate conditions. These results highlight the importance of strategically locating DSC-MAR projects at the confluence of reliable supply and favorable subsurface hydrologic properties.

Relative importance of landscape versus local wetland characteristics for estimating wetland denitrification potential.

Wetlands can be significant sinks for Nr, via denitrification. There is a lack of understanding about factors controlling denitrification. Research suggests that hydrology, geomorphology, and nitrogen loading are dominant controls. We compared site-scale characteristics with denitrification enzyme activity (DEA) in wetlands along gradients of drainage basin land use to explore the relative importance of landscape and site-scale factors for determining denitrification potential. DEA rates ranged between 0.01-1.69 (μg N gdw-1 hr-1), with most sites falling at the lower end. Sites with higher DEA rates had higher percentages of soil carbon and nitrogen, concentrations of soil extractable NO3 and percent loss on ignition. Sites with upstream agricultural activity had higher DEA rates than more natural sites, but there existed a wide range of DEA rates along both agricultural and urban land gradients. When multiple site and landscape-scale explanatory factors were compared to DEA rates, two site and one landscape scale characteristic (Soil NO3, Soil Percent N, and Percent Agriculture) had significant (p<0.001, cum. r2 = 0.77) correlations with DEA rates. Our results suggest that DEA is controlled mainly by local-scale site characteristics with more work needed to determine the interdependencies and relative importance among these and potentially related landscape-scale factors.

Characteristics of forest landscape fragmentation in Lam River basin

Forest fragmentation of the Lam basin was studied with the aid of the Infragmentation tool in GIS, with satellite imagery and current basin land use maps. The results show that the forest landscape of the Lam basin is fragmented into four main types: core forest, patch forest, edge forest and perforated forest, of which the core forest occupies the largest area and is divided into three categories: small core forest, medium core forest and large core forest. The forest landscape in the upper of Lam River varies from 2007 to 2017 with the following major trends: large core forest area increased 2.5%, the rest reduced.