Land Use Changes In Watershed Research Articles

AVALIAÇÃO DO USO E OCUPAÇÃO DO SOLO NA BACIA HIDROGRÁFICA DO RIO ITAJAÍ E SIMULAÇÃO PARA 2027

A característica do uso do solo, o estado de regeneração das florestas e as práticas das atividades econômicas locais – principalmente as práticas agrícolas – influenciam diretamente na qualidade e na quantidade de água em uma bacia hidrográfica. O objetivo deste estudo é apresentar uma avaliação da evolução do uso e ocupação do solo na bacia hidrográfica do rio Itajaí, que possui uma área total de aproximadamente 15 km², e é uma das mais importantes do estado de Santa Catarina. Foram avaliados mapas de uso do solo dos anos de 1990, 2000, 2010 e 2015, obtidos por meio do projeto MapBiomas. A partir da avaliação da evolução do uso do solo, com o auxílio do software TerrSet, antigo IDRISI, foi simulado um mapa de uso do solo para o ano de 2027. Os resultados indicaram que a área total de silvicultura, principal atividade causadora de desmatamento na bacia, terá um crescimento de 48,1%, enquanto que a área total de florestas naturais terá uma redução de 13,2%. Estima-se que, em 2027, apenas 55% da área total da bacia seja de florestas naturais. Em 1990, este valor era de 67%.

Land use changes impact on water quality in Jeneberang Watershed, South Sulawesi, Indonesia

Land use change and water quality problems occur in most watersheds in Indonesia, which are also resulted by climate change phenomenon. One of the watersheds that have a critical status but have an important role in South Sulawesi, Indonesia is the Jeneberang watershed, which is included in 15 national priority watersheds for restoration and conservation. The purpose of this study is to analyze the impact of land use changes in watersheds over the last 20 years on water quality. This research is a descriptive study using quantitative and qualitative methods. In this study, Land Change Modeler (LCM) module was used in Idrisi Terrset software to analyze changes in used/covered by comparing the imagery of 2000 and 2020, while water quality analysis using the pollution index method on 7 key parameters of water quality. The results showed a decrease in forest area cover in the upstream part of the watershed with an increase in the area of agricultural areas and settlements. Water quality was classified as lightly polluted with the pollution index values increased from upstream (2.04), middle (2.12,) to downstream (2.83). Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Coliform concentrations were higher than national standards of water quality. Changing land use into agricultural areas and settlements has contributed to increased water pollution in the Jeneberang watershed.

Analysis of infiltration and surface runoff using rainfall simulator with variation of rain intensity and vegetation

Changes in watershed land use are a concern due to the increase of flood from year to year which can harm the community both material and non-material. Meanwhile, during the dry season there was a significant decrease and causes irrigation water supply and clean water for daily needs to decrease and even to dry. Surface runoff and infiltration in a watershed area becomes an inseparable unit, with increasing surface runoff causing big flooding, flash floods and reducing infiltration, causing less groundwater supply to maintain river availability tend to decrease. The testing of vegetation effect on watershed areas on surface runoff and infiltration with a rainfall simulator was to analyze the extent of the role of vegetation in rainfall intensity with surface runoff and infiltration on rainfall intensity. Tests were carried out using a rain fall simulator using intensities I2 and I5 on two types of vegetation selected at the location of Maros watershed, namely mango and bamboo vegetation. The results show that changes in land cover increase surface runoff and reduce infiltration. So that land use should not be carried out carelessly and still have to pay attention to the sustainability of the function of the forest as river water retention. Land damage will be responded to by unexpected flooding and disruption of the land ecosystem, causing the extinction of flora and fauna habitat to become an indicator of increasingly critical land damage.

Assessing δ15N values in the carbonate-bound organic matrix and periostracum of bivalve shells as environmental archives

Though previous studies demonstrate the utility of nitrogen and carbon stable isotope ratios (δ15N and δ13C, respectively) in bivalve soft tissues as biogeochemical proxies, it is necessary to develop alternative proxies for environmental reconstructions when soft tissues are unavailable, such as with fossils or in museum-archived specimens. This study assesses the reliability of the δ15N values of carbonate-bound organic matrix (δ15NCBOM) and periostracum (δ15Nperiostracum) in bivalve shells as recorders of the δ15N values of particulate nitrogen (δ15NPN) by comparing the δ15NCBOM and δ15Nperiostracum values of live-collected freshwater mussels (Elliptio complanata) and estuarine clams (Rangia cuneata) to the δ15N values of particulate nitrogen (δ15NPN) in the water column. The δ15NCBOM and δ15Nperiostracum values in both species were within the range of the δ15NPN values that have been corrected for trophic-level enrichment. Thus, our findings illustrate that δ15NCBOM and δ15Nperiostracum values reliably record δ15NPN values in rivers and estuaries. The significant positive correlation between δ15NCBOM and δ15Nperiostracum values in both species indicates that they may be used in a similar manner to record δ15NPN values. The δ15N values in E. complanata muscle, mantle, and gill tissues were enriched by about +3.4‰ compared to δ15NPN from the water column, which suggests that they are primary consumers that reflect baseline trophic levels. On the other hand, δ15N values in the soft tissues of R. cuneata have trophic-level enrichment consistent with both primary and secondary consumption. Therefore, variations in the δ15N values of tissues in R. cuneata may be related to trophic-level shifts and/or changes in N sources. Differences between the δ15N values of soft tissue, CBOM, and periostracum in E. complanata and R. cuneata can be attributed to asynchronous growth, metabolic rate, and organic molecule composition. The δ15NCBOM values vary along a freshwater-estuarine gradient because of land-use change and differences in the trophic level of the compared species. The δ15NCBOM values between neighboring sites reflect influences from biosolid application and treated wastewater discharge. While δ15NCBOM values did not differentiate between sites dominated by urban and forested land-cover, δ15NCBOM values were highest at the site with the highest agricultural land-use. These results demonstrate the potential of δ15NCBOM values in bivalve shells to record long-term changes in watershed land use.

Understanding Anthropogenic Impacts on pH and Aragonite Saturation State in Chesapeake Bay: Insights From a 30‐Year Model Study

AbstractOcean acidification (OA) is often defined as the gradual decline in pH and aragonite saturation state (ΩAr) for open ocean waters as a result of increasing atmospheric pCO2. Potential long‐term trends in pH and ΩAr in estuarine environments are often obscured by a variety of other factors, including changes in watershed land use and associated riverine carbonate chemistry and estuarine ecosystem metabolism. In this work, we investigated the anthropogenic impacts on pH and ΩAr over three decades (1986–2015) in Chesapeake Bay using retrospective coupled hydrodynamic‐biogeochemical model simulations. Simulation results demonstrated a clear estuarine acidification signal in the midbay region, with a long‐term increase in the annual duration of acidified bottom waters (pH < 7.5, ~2 days/yr) as well as a shallowing of the saturation horizon (~0.1 m/yr). In contrast, scenario results revealed basification in the upper bay consistent with increased alkalinization of the Susquehanna River. Significant long‐term pH and ΩAr declines in the lower bay were driven by nearly equal contributions from OA and lowered surface ecosystem production. The midbay pH variability was primarily influenced by OA and biological processes, while river basification along with OA played a key role in regulating the long‐term ΩAr variability. This study quantifies the contributions from multiple anthropogenic drivers to changes in estuarine carbonate chemistry over three decades, highlighting the complex interactions in regulating the dynamics of pH and ΩAr and informing regional natural resource management and ecosystem restoration.

“New” cyanobacterial blooms are not new: two centuries of lake production are related to ice cover and land use

AbstractRecent cyanobacterial blooms in otherwise unproductive lakes may be warning signs of impending eutrophication in lakes important for recreation and drinking water, but little is known of their historical precedence or mechanisms of regulation. Here, we examined long‐term sedimentary records of both general and taxon‐specific trophic proxies from seven lakes of varying productivity in the northeastern United States to investigate their relationship to historical in‐lake, watershed, and climatic drivers of trophic status. Analysis of fossil pigments (carotenoids and chlorophylls) revealed variable patterns of past primary production across lakes over two centuries despite broadly similar changes in regional climate and land use. Sediment abundance of the cyanobacterium Gloeotrichia, a large, toxic, nitrogen‐fixing taxon common in recent blooms in this region, revealed that this was not a new taxon in the phytoplankton communities but rather had been present for centuries. Histories of Gloeotrichia abundance differed strikingly across lakes and were not consistently associated with most other sediment proxies of trophic status. Changes in ice cover most often coincided with changes in fossil pigments, and changes in watershed land use were often related to changes in Gloeotrichia abundance, although no single climatic or land‐use factor was associated with proxy changes across all seven lakes. The degree to which changes in lake sediment records co‐occurred with changes in the timing of ice‐out or agricultural land use was negatively correlated with the ratio of watershed area to lake area. Thus, both climate and land management appeared to play key roles in regulation of primary production in these lakes, although the manner in which these factors influenced lakes was mediated by catchment morphometry. Improved understanding of the past interactions between climate change, land use, landscape setting, and water quality underscores the complexity of mechanisms regulating lake and cyanobacterial production and highlights the necessity of considering these interactions—rather than searching for a singular mechanism—when evaluating the causes of ongoing changes in low‐nutrient lakes.

Headwater Stream Microbial Diversity and Function across Agricultural and Urban Land Use Gradients

Anthropogenic activity impacts stream ecosystems, resulting in a loss of diversity and ecosystem function; however, little is known about the response of aquatic microbial communities to changes in land use. Here, microbial communities were characterized in 82 headwater streams across a gradient of urban and agricultural land uses using 16S rRNA gene amplicon sequencing and compared to a rich data set of physicochemical variables and traditional benthic invertebrate indicators. Microbial diversity and community structures differed among watersheds with high agricultural, urban, and forested land uses, and community structure differed in streams classified as being in good, fair, poor, and very poor condition using benthic invertebrate indicators. Microbial community similarity decayed with geodesic distance across the study region but not with environmental distance. Stream community respiration rates ranged from 21.7 to 1,570 mg O2 m-2 day-1 and 31.9 to 3,670 mg O2 m-2 day-1 for water column and sediments, respectively, and correlated with nutrients associated with anthropogenic influence and microbial community structure. Nitrous oxide (N2O) concentrations ranged from 0.22 to 4.41 μg N2O liter-1; N2O concentration was negatively correlated with forested land use and was positively correlated with dissolved inorganic nitrogen concentrations. Our findings suggest that stream microbial communities are impacted by watershed land use and can potentially be used to assess ecosystem health.IMPORTANCE Stream ecosystems are frequently impacted by changes in watershed land use, resulting in altered hydrology, increased pollutant and nutrient loads, and habitat degradation. Macroinvertebrates and fish are strongly affected by changes in stream conditions and are commonly used in biotic indices to assess ecosystem health. Similarly, microbes respond to environmental stressors, and changes in community composition alter key ecosystem processes. The response of microbes to habitat degradation and their role in global biogeochemical cycles provide an opportunity to use microbes as a monitoring tool. Here, we identify stream microbes that respond to watershed urbanization and agricultural development and demonstrate that microbial diversity and community structure can be used to assess stream conditions and ecosystem functioning.

Beyond the trends: The need to understand multiannual dynamics in aquatic ecosystems

Beyond the trends: The need to understand multiannual dynamics in aquatic ecosystems

Establishment of physico-chemical variables and Chl a criteria based on land-use patterns and terrestrial ecosystem health

Developing numeric criteria is crucial for controlling cultural eutrophication and for protecting current and future water quality. Land-use changes in watersheds are the most important early warning indicators of lake eutrophication. In this study, the relationships between land-use patterns and physico-chemical variables and chlorophyll a (Chl a) concentrations were obtained through stepwise regression analysis to predict physico-chemical and Chl a criteria for the Eastern Plain Ecoregion. Ecological indicators (including landscape, function, and stressor aspects) related to land-use patterns and soil erosion was selected for the assessment of terrestrial ecosystem health using the analytic hierarchy process. The results indicated that the physico-chemical and Chl a criteria estimated from the relationships between anthropogenic land use and water quality variables were similar to the average values of the corresponding variables in the case of excellent terrestrial ecosystem health. The average values of water quality variables corresponding to excellent terrestrial ecosystem health can be used as criteria in the Eastern Plain Ecoregion. These findings are advantageous for understanding the health levels of the terrestrial ecosystems of the shallow lakes in this region and the degree of interference from human activities, as well as for providing a theoretical basis for the determination of criteria.

Long term state of coastal lagoons in Veracruz, Mexico: Effects of land use changes in watersheds on seagrasses habitats

An increase in population over the last 50 years along the central coast of Veracruz on the Gulf of Mexico has led to a corresponding intensification of agriculture, urbanization, and other economic activities. Most significantly, this has resulted in rapid changes of land use and an increase in the area dedicated to agriculture and livestock. Native coastal wetland vegetation has declined significantly, and coastal lagoons systems are altered as they receive excess nutrients and sediments from agricultural and economic activities. The aim of this study was to evaluate the influence of productive activities on four coastal lagoons and one estuary at the watershed level and to establish reference points or ecological indicators upon which future changes in coastal wetlands may be measured. For this purpose we analyzed the physico-chemical characteristics of the water column, assessed the abundance and biomass of seagrasses, and determined the historical and current trophic status of these coastal water bodies. Our results indicate that over time the lagoons have remained in a eutrophic state, and only one has become mesotrophic. The biomass of the seagrass Halodule wrightii decreased by 28% from 1991 to 2001 in La Mancha Lagoon. Our results provide a baseline to assess future changes in the water quality of the selected study sites and the seagrasses populations they contain.

Linking geomorphologic knowledge, RS and GIS techniques for analyzing land cover and land use change: a multitemporal study in the Cointzio watershed, Mexico

It is well-established that changes in land cover and land use (LCLU) are relevant to current local and global changes that are directly linked with food security, human health, urbanization, biodiversity, trans-border migration, environmental refuges, water and soil quality, runoff and sedimentation rates, and other processes. This paper examines LCLU change processes within the Cointzio watershed (Central Mexico). The analysis covers a 28-year time period from 1975 to 2003. LCLU changes were deduced from multi-temporal remote sensing analyses (1975, 1986, 1996, 2000 and 2003). Nearly all of the LCLU changes experienced in the Cointzio watershed occurred during the 1986-1996 period. Half of the 665 km² of the watershed have changed during this period, in what corresponds to a ten-fold increase in the rate of change as compared to the 1975-1986 and 1996-2003 periods. These massive changes are probably related to the Immigration Reform and Control Act (IRCA) of 1986, which limited the transit of undocumented Mexican workers to the United States of America. The methodology applied in this research constitutes a low-cost alternative for evaluating the impact of LCLU change in watersheds. The magnitude of land use change differed during the periods of analyses in the watershed, functional zones and geoforms. The methodological approach applied in this analysis integrates standard procedures to evaluate land cover and land use change in watersheds. Due to the practical value of the results, the data and information generated during the analysis have been made available to local authorities.

Model investigation overthrows assumptions of watershed research

A 2009 study revealed serious flaws in a standard technique used by hydrological researchers to understand how changes in watershed land use affect stream flow behaviors, such as peak flows. The study caused academics and government agencies alike to rethink decades of watershed research and prompted Kuraś et al. to reinvestigate a number of long‐standing assumptions in watershed research using a complex and well‐validated computer model that accounts for a range of internal watershed dynamics and hydrologic processes. For the test site at 241 Creek in British Columbia, Canada, the authors found not only that deforestation increased the severity of floods but also that it had a scaling influence on both the magnitudes and frequencies of the floods. The model showed that the larger the flood, the more its magnitude was amplified by deforestation, with 10‐to 100‐year‐return‐period floods increasing in size by 9%–25%. Following a simulated removal of half of the watershed's trees, the authors found that 10‐year‐return‐period floods occurred twice as often, while 100‐year‐return‐period events became 5–6.7 times more frequent. This proportional relationship between the increase in flood magnitudes and frequencies following deforestation and the size of the flood runs counter to the prevailing wisdom in hydrological science.

Spatiotemporal dynamics of landscape pattern and hydrologic process in watershed systems

Land use change is influenced by spatial and temporal factors that interact with watershed resources. Modeling these changes is critical to evaluate emerging land use patterns and to predict variation in water quantity and quality. The objective of this study is to model the nature and emergence of spatial patterns in land use and water resource impacts using a spatially explicit and dynamic landscape simulation. Temporal changes are predicted using a probabilistic Markovian process and spatial interaction through cellular automation. The MCMC (Monte Carlo Markov Chain) analysis with cellular automation is linked to hydrologic equations to simulate landscape patterns and processes. The spatiotemporal watershed dynamics (SWD) model is applied to a subwatershed in the Blackstone River watershed of Massachusetts to predict potential land use changes and expected runoff and sediment loading. Changes in watershed land use and water resources are evaluated over 100 years at a yearly time step. Results show high potential for rapid urbanization that could result in lowering of groundwater recharge and increased storm water peaks. The watershed faces potential decreases in agricultural and forest area that affect open space and pervious cover of the watershed system. Water quality deteriorated due to increased runoff which can also impact stream morphology. While overland erosion decreased, instream erosion increased from increased runoff from urban areas. Use of urban best management practices (BMPs) in sensitive locations, preventive strategies, and long-term conservation planning will be useful in sustaining the watershed system.

Analysing land cover and land use change processes at watershed level: A multitemporal study in the Lake Cuitzeo Watershed, Mexico (1975–2003)

We analysed land cover change processes over a 28-year time period in Central Mexico, by means of integration of existing databases of land cover and land use (1975 and 2000), and updating through visual interpretation of Landsat MSS and ETM + satellite images and orthophotos (1986, 1996 and 2003). Multitemporal analyses included mapping, evaluation of transition matrices, computation of rates of land use change for the main change processes during each period, and cluster analysis. We used watersheds, subdivided both as sub-watersheds and functional zones, as units of analyses. The processes of land use change in the area were not constant, as most of the land use changes took place over a period of less than ten years. This specific period coincided with both the Immigration Reform and Control Act of 1986, and a major catastrophic earthquake in central Mexico in 1985. Similarly, processes of land use change differed during the periods of analyses in the watershed functional zones. The methodological approach applied in this analysis integrates standard procedures to evaluate land cover and land use change in watersheds. Due to the practical value of the results, the data and information generated during the analysis have been made available to local authorities.

Use of an integrated flow model to estimate ecologically relevant hydrologic characteristics at stream biomonitoring sites

We developed an integrated hydroecological model to provide a comprehensive set of hydrologic variables representing five major components of the flow regime at 856 aquatic-invertebrate monitoring sites in New Jersey. The hydroecological model simulates streamflow by routing water that moves overland and through the subsurface from atmospheric delivery to the watershed outlet. Snow accumulation and melt, evapotranspiration, precipitation, withdrawals, discharges, pervious- and impervious-area runoff, and lake storage were accounted for in the water balance. We generated more than 78 flow variables, which describe the frequency, magnitude, duration, rate of change, and timing of flow events. Highly correlated variables were filtered by principal component analysis to obtain a non-redundant subset of variables that explain the majority of the variation in the complete set. This subset of variables was used to evaluate the effect of changes in the flow regime on aquatic-invertebrate assemblage structure at 856 biomonitoring sites. We used non-metric multidimensional scaling (NMS) to evaluate variation in aquatic-invertebrate assemblage structure across a disturbance gradient. We employed multiple linear regression (MLR) analysis to build a series of MLR models that identify the most important environmental and hydrologic variables driving the differences in the aquatic-invertebrate assemblages across the disturbance gradient. The first axis of NMS ordination was significantly related to many hydrologic, habitat, and land-use/land-cover variables, including the average number of annual storms producing runoff, ratio of 25–75% exceedance flow (flashiness), diversity of natural stream substrate, and the percentage of forested land near the stream channel (forest buffer). Modifications in the hydrologic regime as the result of changes in watershed land use appear to promote the retention of highly tolerant aquatic species; in contrast, species that are sensitive to hydrologic instability and other anthropogenic disturbance become much less prevalent. We also found strong relations between an index of invertebrate-assemblage impairment, its component metrics, and the primary disturbance gradient. The process-oriented watershed modeling approach used in this study provides a means to evaluate how natural landscape features interact with anthropogenic factors and assess their effects on flow characteristics and stream ecology. By combining watershed modeling and indirect ordination techniques, we were able to identify components of the hydrologic regime that have a considerable effect on aquatic-assemblage structure and help in developing short- and long-term management measures that mitigate the effects of anthropogenic disturbance in stream systems.

River Width Adjustment. I: Processes and Mechanisms

In 1993 a Task Committee (TC) of the ASCE was established to study the hydraulics, bank mechanics, and modeling of width adjustment in alluvial channels. The work of the TC in reviewing width adjustment processes and mechanisms is reported in this paper. A companion paper presents the findings of the TC with regard to width adjustment modeling. This paper first establishes the geomorphic context within which width adjustments occur, and it demonstrates that width adjustment may take place over a wide range of scales in time and space. In the past engineering analyses of channel width have tended to concentrate on prediction of the equilibrium width for stable channels. Most commonly the regime, extremal hypothesis, and rational (mechanistic) approaches are used, and these are reviewed herein. More recently, attention has switched to channels that are adjusting their morphology either due to natural instability or in response to changes in watershed land use, river regulation, or channel engineering. Chara...

Nonpoint Pollution and Watershed Management: A Remote Sensing and Geographic Information System (GIS) Approach

ABSTRACT Dallas Water Utilities (DWU) uses Landsat multispectral remote sensing data for determining historical land use changes in watersheds and identifing critical areas where water quality protection efforts should be maximized. Water quality monitoring data are used to document actual impacts to reservoirs from areas predicted by remote sensing analyses to be adversely affected. Additionally, DWU monitors ail National Pollutant Discharge Elimination System (NPDES) and Texas Water Commission waste discharge permit applications and plant performance histories. This ensures that DWU reviews point source discharges and assists the Texas Water Commission in their monitoring functions. DWU cooperates with other area agencies to promote regional wastewater treatment as an alternative to numerous package plants which have a history of poor wastewater management. Point source management should result in lower total nutrient loads to reservoirs. Remote sensing technology provides one of the most efficient meth...

Human Disturbance and the Historical Development of Linsley Pond

Paleolimnological techniques were used at Linsley Pond, North Branford, Connecticut, USA to compare changes in the biota with changes in watershed land use as documented by municipal land records. Fossil diatoms, midges, zooplankton, and chemical composition were examined in a core 238 cm long, which was dated by (210)Pb, (14)C, and changes in fossil pollen assemblages. The beginning of farming in 1700 caused only minor changes in the lake biota. In 1915 changes in agricultural activity at a nearby farm caused a rapid shift to eutrophic diatom and midge assemblages. In 1960 major changes occurred in the zooplankton community in response to the hypereutrophication caused by the construction of a suburban housing development. Fluxes of Fe, Mn, Ca, Cu, and P to the lake sediment seem to be controlled by changes in soil erosion–not by changes in the trophic status of the lake.