Assessment of water quality in Little Vermillion River watershed using principal component and nearest neighbor analyses
4
Citation
28
Reference
10
Related Paper
Citation Trend
Abstract:
Because of increased use of fertilizers to feed the increasing global population, the nutrient loads in surface and subsurface water have increased substantially in the last few decades. Many studies have been conducted to investigate the factors affecting nitrate load in surface and subsurface flow. The objective of this study is to investigate the relationship between the various factors affecting nitrate transport using principal component analysis (PCA) and nearest neighborhood analysis methods. Hydrological and biogeochemical data from a small (<500 km2) agricultural watershed in east central Illinois, USA for the duration of 10 years have been used in this study. The PCA approach divided various factors that influence nitrate transport into three principal components. The first component contained air temperature, cover phenotype, evapotranspiration, cover factor and dry mass factors. The second component contained precipitation and flow, which was defined as the hydrologic component. The third component included tillage practices and nitrogen application and was termed the anthropogenic component. The results from the PCA approach suggested all three components had significant influence on nitrate transportation and transformation. Among these three components, the hydrological components had the highest contribution on both surface and subsurface nitrate load. The nearest neighborhood analysis yielded a similar conclusion.Keywords:
Base flow
Subsurface Flow
Biogeochemical Cycle
This chapter contains sections titled: Introduction Biogeochemical Interactions in Wetland Ecosystems Consequences of Carbon- Nitrogen-Phosphorus Interactions for Plant Species Diversity Relations with Water Table Fluctuations and Water Chemistry Wetland Values Arising from Biogeochemical Functioning: Global Considerations Wetland Values Arising from Biogeochemical Functioning: Guidance for Catchment Management Conclusions References
Biogeochemical Cycle
Biogeochemistry
Cite
Citations (11)
ABSTRACT Watershed planning groups and action agencies seek to understand how lake water quality responds to changes in watershed management. This study developed and demonstrated the applicability of an integrated modeling approach for providing this information. An integrated model linking watershed conditions to water‐quality of the receiving lake incorporated the following components: (1) an event‐based AGNPS model to estimate watershed pollutant losses; (2) annualization of AGNPS results to produce annual lake pollutant loadings; (3) a base flow separation package, SAM, to estimate base flow; (4) estimates of nutrients in base flow and point sources; and (5) linkage of watershed loadings directly to EUTROMOD lake water quality algorithms. Results are presented for Melvern Lake, a 28‐km 2 multipurpose reservoir with a 900‐km 2 agricultural watershed in east central Kansas. Reasonable estimates of current lake quality were attained using an average phosphorus availability factor of 31 percent to calibrate model results to measured in‐lake phosphorus. Comparison of a range of possible scenarios, including all cropland changed to no‐till (best case) and all CRP and good‐condition grasslands changed to cropland (worst case), indicated only a (4 percent change for in‐lake phosphorus and a (2 percent change for chlorophyll a. These results indicated that this watershed is not sensitive to projected changes in land use and management.
Base flow
Watershed Management
Time of concentration
Cite
Citations (30)
Abstract Globally significant quantities of carbon (C), nitrogen (N), and phosphorus (P) enter freshwater reservoirs each year. These inputs can be buried in sediments, respired, taken up by organisms, emitted to the atmosphere, or exported downstream. While much is known about reservoir-scale biogeochemical processing, less is known about spatial and temporal variability of biogeochemistry within a reservoir along the continuum from inflowing streams to the dam. To address this gap, we examined longitudinal variability in surface water biogeochemistry (C, N, and P) in two small reservoirs throughout a thermally stratified season. We sampled total and dissolved fractions of C, N, and P, as well as chlorophyll-a from each reservoir’s major inflows to the dam. We found that heterogeneity in biogeochemical concentrations was greater over time than space. However, dissolved nutrient and organic carbon concentrations had high site-to-site variability within both reservoirs, potentially as a result of shifting biological activity or environmental conditions. When considering spatially explicit processing, we found that certain locations within the reservoir, most often the stream–reservoir interface, acted as “hotspots” of change in biogeochemical concentrations. Our study suggests that spatially explicit metrics of biogeochemical processing could help constrain the role of reservoirs in C, N, and P cycles in the landscape. Ultimately, our results highlight that biogeochemical heterogeneity in small reservoirs may be more variable over time than space, and that some sites within reservoirs play critically important roles in whole-ecosystem biogeochemical processing.
Biogeochemical Cycle
Biogeochemistry
Cite
Citations (5)
The importance of the subsurface response of watersheds has been vastly underrated in most studies of watershed behavior, both in a quantitative sense and in a generic sense. The mechanism of base flow generation and the nature of watershed response in base flow dominant streams are examined with a deterministic mathematical model that couples three‐dimensional, transient, saturated‐unsaturated subsurface flow and one‐dimensional, gradually varied, unsteady channel flow. The channel flow model uses the single step Lax‐Wendroff explicit technique to solve numerically the full shallow water equations. The subsurface flow model uses the line successive overrelaxation technique to solve numerically the Jacob‐Richards diffusion equation. The results of the simulations on a hypothetical basin suggest a wide variability in watershed response under the influence of variations in rainfall properties, antecedent moisture conditions, and saturated and unsaturated subsurface hydrogeologic properties. This evidence for a wide range of watershed response functions leads to the development of a healthy skepticism toward black box rainfall‐runoff correlations, the concept of basin linearity, and the rationality of hydrograph separation.
Base flow
Subsurface Flow
Antecedent moisture
Cite
Citations (243)
Because the biogeochemical cycles of P and Si in temperate lakes are strongly connected by the dynamics of primary producers, it should be possible to influence the former cycle by causing changes in the latter. It is shown using the mathematical model ‘Rostherne’ that winter levels of ambient Si have a major influence both on spring levels of ambient P and on the summer cyanobacterial maxima. Additions of Si to the lakes could be used for the fine regulation of the biogeochemical balance and may prescribe a recipe for improvement of water quality, as well as a new solution to the problem of eutrophication. Copyright © 2000 John Wiley & Sons, Ltd.
Biogeochemical Cycle
Cite
Citations (32)
Abstract Surface runoff (SRO) and shallow‐subsurface flow (SSF) from a small, upland, Coastal Plain watershed underlain by plinthite were monitored for a 10‐y period. Samples collected during surface runoff and subsurface‐flow events were analyzed for NO 3 ‐N. The major water runoff loss from the system was found to be subsurface flow, accounting for 79% of total runoff loss, which occurred primarily from December through May. Nitrate‐N concentrations in surface runoff and subsurface flow were relatively uniform over the period, averaging 0.47 and 8.75 mg/L, respectively. The combination of high volume of subsurface flow and its relatively high NO 3 ‐N content, resulted in 99% of total NO 3 ‐N loss via subsurface flow. Predictive equations for monthly surface and subsurface water runoff losses from this watershed were developed using multiple linear regression. The equations contain seasonal and climatic parameters, including pan evaporation. Tests of the equations with observed results gave significant ( P ≤ 0.01) correlation coefficients, r , of 0.82 and 0.85 for surface runoff and subsurface flow, respectively. Mean surface and subsurface NO 3 ‐N concentrations were multiplied by predicted monthly flows to compute predicted monthly NO 3 ‐N losses. Comparison of predicted and actual monthly NO 3 ‐N losses gave significant ( P ≤ 0.01) correlation coefficients, r , of 0.59 and 0.86 for surface and subsurface flows, respectively. The good fit of predicted and observed results can be partially attributed to the seasonal and climatic data base collected over a relatively long period of 10 y.
Subsurface Flow
Base flow
Cite
Citations (14)
It is the core content to study the biogeochemical circulat io n in wetland in the researches on the wetland ecosystem function.The critical pr ocesses research was developed to investigate the interactions between physical, chemical and biological processes and the relationships between these processes and wetland functions.This paper analyzed the biogeochemical procedures of essen tial elements such as N,P,C,the biogeochemical circulation in wetland.The paper also briefly analyzed the prospects in researches on biogeochemical circulation in wetlands.
Biogeochemical Cycle
Biogeochemistry
Circulation (fluid dynamics)
Cite
Citations (2)
Biogeochemical Cycle
Cite
Citations (0)
A three-equation model for subsurface response is presented. The model is based on storm events for various sized watersheds within the Susquehanna River Basin. The equations represent the peak flow, time to peak, and time base of the subsurface response. The model was developed using multiple variable regression and numerical optimization. The variables used in the regression analysis are related to the physical processes causing subsurface response and were obtained from streamflow and precipitation gauges, a digital elevation model, and land use and soils data. The measured peak subsurface discharge, time to peak, and time base required for the regression analysis were obtained by separating storm hydrographs into direct runoff and subsurface responses. A linear separation from the initial rise of the hydrograph to the inflection point on the recession limb was utilized. The model was developed from a dataset of 50 watersheds by 20 storms (1,000 watershed-events), with the watersheds ranging in size from 14 km2 to 67,000 km2. The results indicate that the measured and predicted subsurface response variables agree well, considering the great variation in the observed responses and the time and space scales of the available data.
Subsurface Flow
Base flow
Base flow
Elevation (ballistics)
Cite
Citations (7)
Synthetic unit hydrograph of a watershed provides a means for studying the hydrologic response of the watershed in absence of stream flow data. Three different approaches, viz. (a) Snyder (1938) method with modification in computation of time base as suggested by Mutreja (1986); (b) Snyder (1938) method with modifications in computations of time to peak as suggested by Linsley et al. (1958) and time base suggested by Mutreja (1986); and (c) computation of time to peak and time base using regression equations as proposed by Gavali et al. (2004) and computation of peak discharge using SCS triangular unit hydrograph theory, were tried to develop synthetic unit hydrograph for a watershed (WS1) at Aagadgaon in Ahmednagar district of Maharashtra State (India) using the pertinent watershed and stream flow data from adjacent watershed (WS2). The third approach seems to be better as it involved more morphological characteristics of a watershed for computation of time to peak and time base of unit hydrograph and least absolute error.
Base flow
Base (topology)
Time of concentration
Cite
Citations (0)