Vassilios A. Tsihrintzis

Modeling and Management of Urban Stormwater Runoff Quality: A Review

Nonpoint source (NPS) pollution from urban runoff has been established as a major cause of receiving water degradation. In an effort to control this problem, new regulations have been passed in the U.S.A. and federal, state, and local agencies are devising urban runoff management programs. This paper reviews recent regulations and studies related to urban stormwater runoff control and planning in the U.S.A.; discusses fundamentals of urban NPS pollution including transport processes and types and sources of pollutants; reviews current hydrologic and water quality mathematical models used in the U.S.A.; presents case studies in both modeling and management; and describes fundamentals of Best Management Practices (BMPs) in urban runoff control. Finally, it summarizes future research needs.

Runoff quality prediction from small urban catchments using SWMM

The RUNOFF block of EPAs storm water management model (SWMM) was used to simulate the quantity and quality of urban storm water runoff from four relatively small sites (i.e. 5·97–23·56 ha) in South Florida, each with a specific predominant land use (i.e. low density residential, high density residential, highway and commercial). The objectives of the study were to test the applicability of this model in small subtropical urban catchments and provide modellers with a way to select appropriate input parameters to be used in planning studies. A total of 58 storm events, measured by the US Geological Survey (USGS), provided hyetographs, hydrographs and pollutant loadings for biological oxygen demand (BOD5), total suspended solids (TSS), total Kjeldahl nitrogen (TKN) and lead (Pb), and were used for calibration of the model. Several other catchment characteristics, also measured or estimated by USGS, were used in model input preparation. Application of the model was done using the Green–Ampt equation for infiltration loss computation, a pollutant accumulation equation using a power build-up equation dependent on the number of dry days, and a power wash-off equation dependent on the predicted runoff rate. Calibrated quantity input parameters are presented and compared with suggested values in the literature. The impervious depression storage was generally found to be the most sensitive calibration parameter, followed by the Mannings roughness coefficients of conduit and overland flow, the Green–Ampt infiltration parameters and, finally, the pervious depression storage. Calibrated quality input parameters are presented in the form of regression equations, as a function of rainfall depth and the number of antecedent dry days. A total of 16 independent rainfall events were used for verification of the model, which showed a good comparison with observed data for both hydrographs and pollutant loadings. Average model predictions for the four constituent concentrations from the verification runs also showed good agreement with NURP published values in Florida and US sites.

A quantitative method for accounting human opinion, preferences and perceptions in ecosystem management

Ecosystem management (EM) is a holistic approach, in which public participation in decision-making, and incorporation of human preferences, needs and perceptions in management plans is a main element. The decision-making from human opinion method (DeMHO), presented here, can be used in EM in selecting the more suitable and socially acceptable management plan, in order to protect or restore an ecosystem. The method focuses on the quantification of the human opinion, preferences and perceptions, which are investigated after research on the local population of the ecosystem. The results of this research are the inputs of the method; multi-criteria decision-making procedures, such as the analytic hierarchy process (AHP), the expected utility method (EUM) and compromise programming (CP) are used to assign the appropriate weights and rank according to their importance the interest groups, the issues to be studied, and the alternative management plans. The alternatives are also evaluated by assessing their sustainable character. The paper presents DeMHO and its application in the National Park of Eastern Macedonia and Thrace in Greece, after a research through a questionnaire on the local population.

Use of Geographic Information Systems (GIS) in water resources: A review

Increasing public awareness, stricter measures and promulgation of new laws in the area of water resources have made the use of advanced technologies indispensable. Geographic Information Systems (GIS) are an effective tool for storing, managing, and displaying spatial data often encountered in water resources management. The application of GIS in water resources is constantly on the rise. In order to stress the importance of GIS in water resources management, applications related to this area are addressed and evaluated for efficient future research and development. Fundamentals of GIS are summarized and the history of the GIS evolution in water resources is discussed. Current GIS applications are presented including surface hydrologic and groundwater modeling, water supply and sewer system modeling, stormwater and nonpoint source pollution modeling for urban and agricultural areas, and other related applications. Future research and development needs are presented, based on these reviews.

Performance and cost comparison of a FWS and a VSF constructed wetland system

The biodegradation of municipal solid waste (MSW) was investigated in simulated bioreactor landfills under aerobic conditions. The bioreactors were operated to determine Two constructed wetland systems, treating domestic wastewater, are compared in terms of performance and costs. One is a free water surface (FWS) wetland system located in Pompia, Crete, south Greece, and the other one is a vertical subsurface flow (VSF) wetland system located in Gomati, Chalkidiki, north Greece. The FWS system is designed for 1200 p.e. Its construction cost was €305,000, and the capital, operation and maintenance cost was €22.07 p.e.−1 yr−1 or €0.50 m−3 of influent. The VSF system is designed for 1000 p.e. Its construction cost was €410,850, and the capital, operation and maintenance cost was €36.81 p.e.−1 yr−1 or €0.56 m−3 of influent. Both systems achieved high removal rates for BOD5, COD, TSS, TKN, phosphorus, TC, and FC, which makes them ideal for small communities in the Mediterranean region.

Water Quality Trends in a Coastal Lagoon Impacted by Non-point Source Pollution after Implementation of Protective Measures

Water quality data from two different monitoring periods are used to evaluate the trophic state and effectiveness of various protective measures on the restoration of a eutrophic, coastal Mediterranean lagoon. Main protective measures included elimination of municipal/industrial raw wastewater discharges in the rivers outflowing to the lagoon, sediment/erosion control practices in the lagoon’s drainage basin (i.e., construction of sediment/debris dams and grade control structures, reforestation and ban on livestock grazing), and reduction of fertilizer application quantities as a result of changes in crops. Water quality data include, among others, chlorophyll a, dissolved oxygen and nutrient concentrations, various physicochemical parameters, and transparency, measured during two monitoring periods, i.e., before (1983–84) and after (1998–99) implementation of protective measures. Rainfall depth for the two time periods was also available. Empirical equations were developed, from statistical analyses of the data, relating the water quality parameters during the two monitoring periods. These models help identify water quality trends. Based on the analyses, it seems that measures were effective in reducing sediments transported into the lagoon. However, the lagoon remains eutrophic to hypereutrophic, mostly due to phosphorus released in the water column from bottom sediments. Therefore, future restoration efforts should be directed towards the management of bottom sediments.

South Florida greenways : a conceptual framework for the ecological reconnectivity of the region

Abstract A regional greenway network is proposed to reconnect ecologically the fragmented landscapes of south Florida. The natural landscapes of the region have been progressively fragmented on account of agricultural and urban development. It is proposed that the regional system of drainage canals and reservoir levees, which was originally developed to facilitate agriculture and urbanization, be ecologically reclaimed and managed to become a network of environmental restoration and cultural opportunity for south Florida. The existing regional system of drainage canals and reservoir levees is restrictively underutilized. In general, the value of utility and transportation corridors as natural and cultural resources has not been fully appreciated in south Florida. Their value as resources lies in the ample opportunity they offer for landscape revegetation, wetland reclamation, habitat restoration, and community education and recreation. In particular, the existing regional system of drainage canals and reservoir levees represents an extensive resource that can naturally and culturally link the fragmented landscapes of south Florida while maintaining flood control and water conservation. A tripartite method, based on the ecological principles of island biogeography theory and landscape network theory, is used to consider the geographical, morphological, and topological impact on natural diversity and cultural use. Respectively, the effects of network corridor area, network corridor width, and network connectivity and circuitry are described, analyzed, and evaluated for their potential effect on natural diversity and cultural use along the existing regional system of drainage canals and reservoir levees. Results indicate that the proposed regional greenway network is characterized by a large area, broad extent, morphological diversity, and topological connectivity. Variation in greenway structure and function along the regional network can accommodate a multitude of environmental concerns and cultural needs faced by the region. The regional greenway network affords ample flexibility, with three types of corridors (line, strip, and stream) within four types of context (urban, suburban, rural, and natural). Recommendations are made to appraise opportunities further at the regional level, conduct ecological corridor research at the landscape scale, and develop a greenway prototype at a specific community site.

On-site treatment of domestic wastewater using a small-scale horizontal subsurface flow constructed wetland

A small-scale horizontal subsurface flow constructed wetland, located in North Greece, was designed and constructed to treat wastewater from a single-family residence. A three-year monitoring program was undertaken to evaluate the performance of this system. The monitoring campaigns were organized every 7 days. Water quality samples were collected at the inlet, at intermediate points (i.e. at the end of each treatment stage) and at the outlet of the system. Temperature, electrical conductivity, pH and DO were measured in-situ with the use of appropriate instruments at the same points of water sample collection. Water samples were analyzed for BOD, COD, TKN, ammonia, nitrate, nitrite, total phosphorus (TP), ortho-phosphate (OP), total suspended solids (TSS) and total coliforms (TC). Mean removal efficiencies for the monitoring period were: 86.5% for BOD, 84.6% for COD, 83.7% for TKN, 82.2% for ammonia, 63.1% for OP, 63.3% for TP, 79.3% for TSS and 99.9% for TC. Furthermore, based on statistical testing, TKN, ammonia and TP removal efficiencies showed dependence on temperature. The paper presents facility description, study details and monitoring results. The study shows that the use of constructed wetlands in wastewater treatment is a good option for single-family residences in rural areas.

Hydraulic Resistance Determination in Marsh Wetlands

Restoration of degraded and creation of constructed wetlands require proper hydraulic design. Of particular importance is the accurate determination of flow resistancefactors and the proper use of resistance equations, somethingessential for computing basic hydraulic parameters, such as depth and velocity, and for modeling the hydrodynamics of the system. In this study, selected previous theoretical, laboratoryand field studies on wetlands and vegetated-channel hydraulics are reviewed, and existing data from these studies are extractedand compiled in a common database. Resistance determining parameters are discussed, and results are summarized and presented, aiming at obtaining laws governing the flow, and deriving values for frictional factors under various flow scenarios. Graphs of Darcy-Weisbach f or Mannings n versus appropriate hydraulic parameters are presented.A modified n-VR graph is also presented, appropriate for marsh preliminary hydraulic analyses and design. These graphs also indicate missing information and can guide in future research.

Soil salinization in the agricultural lands of Rhodope District, northeastern Greece

The objective of this study was to identify seasonal and spatial trends and soil salinization patterns in a part of Rhodope District irrigated land, northeastern Greece, located east of Vistonis Lagoon. The study area is irrigated from a coastal aquifer, where salt water intrusion occurs because of extensive groundwater withdrawals. Fourteen monitoring sites were established in harvest fields in the study area, where soil samples were collected. Electrical conductivity (ECe), pH, and ion concentrations were determined in the saturated paste extract of the soil samples in the laboratory using standard methods. A clear tendency was observed for ECe to increase from April to September, i.e., within the irrigation period, indicating the effect of saline groundwater to soil. In the last years, the change from moderately sensitive (e.g., corn) to moderately tolerant crops (e.g., cotton) in the south part of the study area indicates the impacts of soil salinity. The study proposes management methods to alleviate this problem.