Hydrogeomorphic considerations in development planning and stormwater management,central Texas Hill Country,USA

Watershed ordinances in Austin, Texas, USA, are intended to protect streams from stormwater degradation. Their adequacy is being questioned, however, where development is advancing into the Hill Country northwest and southwest of the city. Detailed investigation into hillslope runoff reveals that several important facts were overlooked in the ordinances, including locally high infiltration rates and drainage basins, which function as partial area systems. As a result, development planning is not taking advantage of the natural mitigation potential of the land. Roads cut across infiltration and moisture retention areas on side slopes, enlarging the partial area system feeding streams with stormflows. In addition, most residential planning is not responsive to the stepped microtopography of Hill Country drainage basins and the critical scale at which local runoff processes operate. Recommendations include adjusting the scale and configuration of development to conform with local runoff processes and features and taking advantage of the water-absorbing capacities of basin side slopes. The lesson for ordinance writers is that standard models of community stormwater ordinances are not appropriate for all terrains, especially complex ones like the Texas Hill Country.     

THE CIRCUIT RIDING ORDINANCE ADMINISTRATOR: A SOLUTION TO SMALL COMMUNITY TECHNICAL INADEQUACIES1

ABSTRACT: Small, rural communities (less than 2500 population) in general do not have governmental staffs with the breadth required to satisfactorily implement and enforce a drainage ordinance. This fact has serious implications in rural Planning. Within a six-country rural area of Southwest Virginia, the circuit riding town manager program has been successfully conducted. The circuit riding town manager is a planning staff member who acts in the capacity of a town manager (assistant to the mayor) for five small towns, any one of which alone could not afford to support the services of such a professional. This note recommends that a circuit riding technical ordiance administrator program could be developed along the same lines. In this manner, the technical ordinance program for serveral small communities could be successfully implemented.     

EMERGING STATE ROLES IN URBAN STORMWATER MANAGEMENT1

ABSTRACT: The technology of urban stormwater management has far outpaced its actual application in new urban development. This article documents that implementation gap, but shows that state and local governmental measures, particularly storm drainage regulations, can lead to improved performance in the private sector. Although state stormwater management programs are in their infancy, they are already having a measurable effect in stimulating the adoption of local governmental programs to manage urban storm water. Pioneering state programs in Maryland, New Jersey, and Pennsylvania, described in this article, provide models for states contemplating the formulation of stormwater management programs.     

Evaluating Infiltration Requirements for New Development Using Extreme Storm Transposition: A Case Study from Dane County,WI

Changes in land use and extreme rainfall trends can lead to increased flood vulnerability in many parts of the world, especially for urbanized watersheds. This study investigates the performance of existing stormwater management strategies for the Upper Yahara watershed in Dane County, WI to determine whether they are adequate to protect urban and suburban development from an extreme rainfall. Using extreme storm transposition, we model the performance of the stormwater infiltration practices required for new development under current county ordinances. We find during extreme rainfall the volume of post‐development runoff from impervious surfaces from a typical site would increase by over 55% over pre‐development conditions. We recommend the ordinance be strengthened to reduce vulnerability to flooding from future urban expansion and the likely increase in the magnitude and frequency of extreme storms.     

A Case Study of Form-Based Solutions for Watershed Protection

Despite an array of policies at the federal and state level aimed at regulating stormwater discharges, engineered solutions enforced by local governments often fall short of meeting water quality standards. Although the implications of land use planning and development regulations are important for stormwater management, they are often overlooked as critical initial steps to improving water quality. This study explores the role of ‘form-based’ regulations as tools for achieving urban planning and water quality objectives. Form-based codes are a new generation of development codes aimed at regulating urban development based on urban form and density, rather than land use. We present an exploratory case study of the feasibility of form-based codes in the Jordan Lake Watershed in North Carolina, a rapidly growing region where fragmented local governments face stringent nutrient reduction standards under new state regulations. Through program analysis and interviews, we explore the viability of form-based codes for reducing development impacts on Jordan Lake’s water quality. We consider the legal feasibility of code enforcement, regional and local barriers and opportunities, and implementation given existing regulatory frameworks. Our findings suggest that high quality information and data modeling are foundational to gaining support for a consensus agreement on the sources and degree of water quality impairment. Furthermore, implementing form-based solutions for water quality is greatly aided by (1) experienced regional planning bodies that have regulatory authority, and (2) local governments whose staff are experienced in implementing complex development ordinances, reviewing architectural renderings, and communicating development requirements with the public and developers.     

THE LOCAL-STATE-FEDERAL TEAM APPROACH TO FLOODPLAIN MANAGEMENT1

Results of the establishment of a Local Flood Relations program in 1953 by TVA are discussed. In 16 years TVA has produced local floodplain information reports for 126 communities. As of September 1, 1969, 66 valley communities had adopted floodplain provisions in their zoning ordinances or subdivision regulations, or both. The local-state-Federal team approach to floodplain management is viable and any other appears to be doomed to failure. A floodplain management program can be expected to succeed as a collaborative effort at all levels of government, each playing the part and assuming the responsibilities best fitted to it. Most of us now accept that our flood problems will not be solved by engineering works alone or even in combination with upstream land management. The solution requires a linking of broad community planning with traditional engineering works. This means that the local, state, and Federal objectives and policies must be effectively coordinated. This method has been developed and satisfactorily applied in the Tennessee Valley during the past decade. The need for more effective means for coping with mounting local flood losses was recognized by the Tennessee Valley Authority and led to the establishment of its Local Flood Relations program in 1953. Since a working relationship with the people of the Valley and their state and local institutions had been carefully nurtured by TVA for over twenty years, it was only natural that the new program would also be a cooperative one.     

Environmental evaluation of subdivision site developments

An environmental evaluation was performed at 16 subdivision sites within four communities in east-central Michigan. The primary objective was to evaluate the fit between environmental ordinances and the physical/environmental conditions to which they were applied. An environmental response index was developed with indicators to assess water, soil, slope, development density, roads, vegetation, and ecology. Water-related indicators achieved the highest scores, while soil-related indicators scored the poorest, with generally poor performance across all indicators. The poor performance indicates there are problems in the ability of environmental ordinances developed at broader jurisdictional scales (e.g., the state) to address the existing environmental conditions at smaller geographic scales (subdivisions within communities). Two key problems include the lack of scientific specificity in the broader state-level ordinances and the lack of local expertise and/or resources to monitor the environment.     

Environmental Evaluation of Subdivision Site Developments

An environmental evaluation was performed at 16 subdivision sites within four communities in east-central Michigan. The primary objective was to evaluate the fit between environmental ordinances and the physical/environmental conditions to which they were applied. An environmental response index was developed with indicators to assess water, soil, slope, development density, roads, vegetation, and ecology. Water-related indicators achieved the highest scores, while soil-related indicators scored the poorest, with generally poor performance across all indicators. The poor performance indicates there are problems in the ability of environmental ordinances developed at broader jurisdictional scales (e.g., the state) to address the existing environmental conditions at smaller geographic scales (subdivisions within communities). Two key problems include the lack of scientific specificity in the broader state-level ordinances and the lack of local expertise and/or resources to monitor the environment.     

AN EXTENSION INFORMATION PROGRAM TO IMPROVE RESIDENTIAL WELL WATER QUALITY1

ABSTRACT: Older inland lake communities in Wisconsin are more likely than many areas to have degraded water supplies. Many home sites are on sandy soils with high water tables and have shallow wells close to their own or a neighbor's septic system. Yet unless major rehabilitation is undertaken, these homes are relatively exempt from local codes and regulations. They also are beyond the application of the federal Clean Drinking Water Act. An Extension education program was created in response to the problem. At a community's request, home drinking water “screening tests” are conducted for at least coliform bacteria, chlorides, and nitrate/nitrite-N. Test results, together with explanations and recommendations are reported at a local meeting. Public response has been positive, and a surprising number of wells appear to be contaminated to some degree.     

ALTERNATIVES TO THE USE OF AGRICULTURAL DRAINAGE WELLS1

ABSTRACT: A large number of agricultural drainage wells (ADWs) are located in north-central Iowa. These wells permit sediments, pesticides, nitrate, and bacteria in surface and subsurface drainage water to enter regional aquifers that are currently being used for drinking-water supplies, mostly by rural families and communities. This paper reports some possible alternatives to control the entry of surface and subsurface drainage waters into groundwater systems, and describes a methodology to make comprehensive economic feasibility studies of alternative drainage outlets. The estimated cost of providing main subsurface drains varied from $220 to $960 per hectare. If the use of ADWs was completely eliminated without providing alternative drainage, it is estimated that the average annual loss to the farmers of the area would be at least $270 per hectare in reduced crop yields. Of course, losses would be weather dependent and highly variable. Management practices to reduce the pollutant load in water draining to ADWs are also discussed.     

STORM WATER MANAGEMENT: THE CONCEPT AND ITS APPLICATION1

ABSTRACT: Storm water management is a concept being applied in many urban areas to deal with the increasing problems of storm runoff control and flood damage prevention. This paper introduces the concept and describes the recently completed storm water management program in Columbus, Georgia. Columbus has spent five years and over $200,000 in the development of their problem which includes several basic elements: soils inventory and analysis, hydrologic data collection, sediment and erosion control ordinance, storm water management handbook, urban flood simulation model, interdepartment coordination study, drainage problem categorization study, and a pilot basin study. The results of the pilot basin study are presented including example output from the urban simulation model. The computer output illustrates both the hydrologic-hydraulic and economic capabilities of the model.     

古树名木保护地方立法评析与建议

对我国出台的15部古树名木保护地方性法规和规章出台时间、主要内容进行了归纳分析。结果发现:法规和规章中存在着管理体制不顺、权责利不对等、处罚标准不合理等问题。在研究基础上,提出完善古树名木保护立法的建议:加快推进古树名木保护国家立法,逐步完善地方立法,进一步理顺保护管理体制,建立古树名木保护补偿制度,加强科学研究与技术推广等。     

Open data and stormwater systems in Los Angeles: applications for equitable green infrastructure

Urban stormwater systems traditionally used “grey” infrastructure to manage runoff. Contemporary designs now incorporate “green” infrastructure, which offers additional potential benefits such as urban amenities and health. Understanding how green and grey infrastructure investments are distributed across urban areas is important for new goals of promoting environmental justice in planning. In California, for instance, public investments increasingly require a percentage of funds to be spent in disadvantaged communities. Recent advancements in the availability of high-detail geographic data in cities can support prioritising investments to fulfil these multiple benefits. This paper analyses the distribution of stormwater infrastructure in Los Angeles (LA) County in relation to design criteria, urban structure and sociodemographic information. It demonstrates an approach for identifying projects that simultaneously address engineering needs and promote equity. Statistical analysis of high-detail sewer locations reveals geographic correlations with key local design parameters, urban characteristics and sociodemographic indicators. Watershed areas in LA County were identified that support multi-benefit projects, meeting dual criteria for infrastructure improvements and disadvantaged community status. As stormwater systems are increasingly designed for multi-benefit outcomes, new design frameworks can emphasise both performance and social equity.     

Environmental regulatory failure and metal contamination at the Giap Lai pyrite mine, Northern Vietnam

The causes for the failure in enforcement of environmental regulations at the Giap Lai pyrite mine in northern Vietnam are considered and the environmental impacts that are associated with this mine are evaluated. It is shown that sulphide-rich tailings and waste rock in the mining area represent significant sources of acid rock drainage (ARD). The ARD is causing elevated metal levels in downstream water bodies, which in turn, represent a threat to both human health and to aquatic ecosystems. Metal concentrations in impacted surface waters have increased after mine closure, suggesting that impacts are becoming progressively more serious. No post-closure, remediation measures have been applied at the mine, in spite of the existence of environmental legislation and both central and regional institutions charged with environmental supervision and control. The research presented here provides further emphasis for the recommendation that, while government institutions may need to be strengthened, and environmental regulations need to be in place, true on the ground improvement in environmental quality in Vietnam and in many other developing countries require an increased focus on promoting public awareness of industrial environmental issues.     

AN INTEGRATED ONE‐DIMENSIONAL AND TWO‐DIMENSIONAL URBAN STORMWATER FLOOD SIMULATION MODEL1

ABSTRACT: Flash flooding is the rapid flooding of low lying areas caused by the stormwater of intense rainfall associated with thunderstorms. Flash flooding occurs in many urban areas with relatively flat terrain and can result in severe property damage as well as the loss of lives. In this paper, an integrated one‐dimensional (1‐D) and two‐dimensional (2‐D) hydraulic simulation model has been established to simulate stormwater flooding processes in urban areas. With rainfall input, the model simulates 2‐D overland flow and 1‐D flow in underground stormwater pipes and drainage channels. Drainage channels are treated as special flow paths and arranged along one or more sides of a 2‐D computational grid. By using irregular computation grids, the model simulates unsteady flooding and drying processes over urban areas with complex drainage systems. The model results can provide spatial flood risk information (e.g., water depth, inundation time and flow velocity during flooding). The model was applied to the City of Beaumont, Texas, and validated with the recorded rainfall and runoff data from Tropical Storm Allison with good agreement.     

On how environmental stringency influences adoption of best management practices in agriculture

There are relatively few Federal environmental regulations that influence agricultural production in the US. However, many local and state environmental rules may influence the management practices on US farms as might interactions between urban population centers and agricultural producers. Detailed analysis of corn farms gives insight into these relationships and suggests that stringent environmental regulations could increase the likelihood of adoption of certain conservation practices, all else being constant, but that the interaction between urban populations has less of an effect on the adoption decisions.     

Illinois State Water Survey Bulletin 75: New Precipitation Frequency Study for Illinois

Storm frequency estimates and their temporal distributions are important in determining estimates of runoff or peak flow rates in many engineering and hydrological problems. Illinois State Water Survey Bulletin 70 has been serving as the design rainfall standard in Illinois since its publication in 1989. Although Bulletin 70 represented the best available data at the time of its publication, the standards needed to be reevaluated and updated after more than three decades and with the growing evidence of the nonstationary nature of heavy precipitation. The trends in heavy precipitation in Illinois prompted the creation of a new frequency study named Bulletin 75, providing precipitation frequencies for event durations ranging from 5 min to 10 days and for recurrence intervals ranging from 2 months to 500 years. The results are presented for the same 10 geographic sections in Illinois as in Bulletin 70 to maintain the continuity of hydrologic studies and compatibility with regulations. The primary goal of this paper is to outline some of the key methodological issues and challenges, to compare the results with the previous sources, and to highlight the effects of the changing precipitation standards on the development of amendments to existing ordinances. Lake County in Illinois, as one of the most affected urban areas with the highest change in heavy precipitation, was selected to illustrate issues related to the application of modified precipitation standards.     

Urban/rural division in environmental justice frameworks: revealing modernity-urbanisation nexus in Turkey’s small-scale hydropower development

Environmental justice frameworks predominantly focus on exploration of socio-environmental inequalities faced by racial, ethnic, religious, cultural and low-income groups. This article aims to expand this mainstream focus of the environmental justice concept on these groups by conceptualising urban/rural division as a group difference, based on which rural communities face with socio-environmental burdens of environmental policies in relation to their urban counterparts. It is based on the analysis of Turkey’s small-scale hydroelectricity power plant (HPP) development policies, referring to the planning and constructions of approximately 1500 hydropower plants across the country, along with country’s modernist agenda, i.e. achievement of economic development, social progress and urban transformation of Turkey. These power plants are also strongly associated with numerous socio-economic, environmental and cultural impacts on local rural communities and local environments with dozens of local opposition movements, while favouring needs, interests and lifestyles of urban communities. This point deserves a systematic conceptualisation within the environmental justice frameworks as it helps to further explain deep causes of socio-environmental inequalities particularly in developing country contexts. Thus, this article is built on such a conceptualisation arguing the necessity to integrate urban/rural division as a separate group difference to environmental justice frameworks by examining modernisation and urbanisation nexus in Turkey’s small-scale HPP development process.     

Wetland cultivation and hydrological management in eastern Africa: Matching community and hydrological needs through sustainable wetland use

Wetlands are critical natural resources in developing countries where they perform a range of environmental functions and provide numerous socio-economic benefits to local communities and a wider population. In recent years, however, many wetlands throughout eastern Africa have come under extreme pressure as government policies, socio-economic change and population pressure have stimulated a need for more agriculturally productive land. Although wetland drainage and cultivation can make a key contribution to food and livelihood security in the short term, in the long term there are concerns over the sustainability of this utilization and the maintenance of wetland benefits. This article draws upon recent research carried out in western Ethiopia, which addressed the sustainability of wetland agriculture in an area of increasing food insecurity and population pressure. It discusses the impacts of drainage and cultivation on wetland hydrology and draws attention to local wetland management strategies, particularly those characterized by multiple use of wetlands, where agriculture exists alongside other wetland uses. The article suggests that where multiple wetland uses exist, a range of benefits can be sustained with little evidence of environmental degradation. Ways of promoting and empowering such sustainable wetland management systems are discussed in the context of the wider need for water security throughout the region.     

THE IMPACT OF HIGH INTEREST RATES ON OPTIMUM MULTIPLE OBJECTIVE DESIGN OF SURFACE RUNOFF URBAN DRAINAGE SYSTEMS1

ABSTRACT. This research examines the impact of high rates of interest upon the least cost system design for urban drainage systems when water quality is a critical parameter. Results of examination of twelve alternative system designs in a case study watershed indicate the least cost study design is highly sensitive to the rate of interest, but not sensitive to the water quality parameters. When the high rates of interest currently prevalent are introduced into the model those systems which contain open channel collection components are selected as the least cost system. At low rates of interest pipeline collection components are selected as the least cost system. Holding pond components of system design are cost effective at several levels of water quality. They are neutral to the rate of interest so they are incorporated in least cost systems at all the levels of interest rates. The results of the study indicate that at the current high rates of interest open channel collection systems and holding ponds are cost effective system components to achieve selected levels of water quality in urban drainage system design.