Processes,feedbacks, and morphodynamic evolution of tidal flat–marsh systems: Progress and challenges

Tidal flats and saltmarshes have been a long-standing research focus because of their high socio-economic and ecological values. The evolution of tidal flat–marsh systems is highly complex due to the intertwined processes operating over a variety of spatial and temporal scales. As a traditional research highlight, the role of regular hydrodynamic processes such as tides, waves, and river flows have been explored comprehensively with fruitful outcomes. Over past decades, the changing environment (e.g., sea level rise, increasing anthropogenic activities, and extreme weather conditions) has attracted more attention with many reported insightful results. More recent advances indicate that biological activities play a critical role in tidal flat–marsh morphodynamics but are still poorly understood. The field of research that connects the biological and physical processes is commonly described as “biogeomorphology” and requires the joint efforts by scientists from multiple disciplines ranging from hydraulics, ecology, and geography to sociology. This review aims to provide a synthesis of the current research status of tidal flat–marsh morphodynamics, with a particular emphasis on the understanding of various processes and feedbacks underlying the development of morphodynamic models. Some future research needs and challenges are identified to facilitate a more sustainable management strategy for tidal flats and saltmarshes under climate change.     

JAPAN—— Report submitted by： Electricity Infrastructure Division,Ministry of Economy, Trade and Industry, Japan

4 HYDROPOWER DEVELOPMENT 4.1 History of hydropower 4.1.1 Beginning of the development of hydropower In Japan, 1860 to 1890 was thc period of rapid development of the modem State and the establishment of centralized authority. After constructing the framework for the modem State, the Government pursued a policy of economic modernization.New industries were stimulated by establishing Government-managed     

Reservoir Sedimentation in India—Its Causes,Control, and Future Course of Action

ABSTRACT

A survey of Indian reservoirs has shown that they receive on an average about 200 percent more sediment than the design inflow. The causes are the usual, except that they are operating very intensely. In brief ‘misuse and mismanagement’ of the catchment area will describe the causes of higher rates of sedimentation.

Fortunately India is very much aware of this problem and a lot is being done by identifying the priority areas for treatment and implementation of programmes to reduce soil erosion and sediment generation.

While techniques and efficacy of various biological and structural control measures are well known, it is the policy and planning aspects which need greater attention at present. Some of them are:

—It is important that policy and planning should aim at developing the catchment area, reservoir and command area as a package.

—In the developing world sediment is the greatest pollutant and it must be recognised and treated as such.

—A policy for effective water resource and hydropower development, watershed and command area development must take into account the short term and long term, direct and indirect, private and social benefits, and endeavour to involve the people and the employees in such a way that they feel committed to efficient and effective implementation.     

Hydrodynamic modeling of ephemeral flow in the Iishana channel systems of the Cuvelai Basin—Northern Namibia

The transboundary region of the Iishana system in the western Cuvelai Basin, between southern Angola and northern Namibia, is frequently affected by floods at irregular intervals. As a result, the predominantly rural, subsistence farming population has experienced crop failures, human, and economic losses. To date, very little is known about the generation of floods, flood concentration, and stormwater drainage dynamics in this region. In this study, 2D-hydrodynamic modeling was applied to reconstruct one of the latest major flood events during the rainy season from November 2008 to March 2009 in order to study the runoff behavior and interconnectivity of the Iishana system. The model focused on the eastern part of the Iishana system, which was most affected by floods and flood damage due to the high population density in and around Oshakati, the regional capital. Two main streams were identified noteworthy because they merge and subsequently affect Oshakati. Regarding the simulated flood event water depths vary from 0.1 m to 14 m, with an average of 0.2 m, while water depths above 5 m were attributed to borrow pits. The inundation area ranged up to 1860 km² and the amount of water left after the rainy season on March 25th, 2009, was determined between 0.116 and 0.547 km³, depending on the amount of evapotranspiration considered in the model. Thus, in the Angolan part of the Iishana system, significantly larger quantities of water are available for longer periods of time during the subsequent dry season, whereas the system in Namibia stores less water, resulting in a shorter water retention period.     

Large Lake Models—Uses,Abuses, and Future

Mathematical modeling has played and should continue to play an important role in Great Lakes management and scientific development. Great Lakes modeling is entering a phase of relative maturity in which expectations are more realistic than in the past. For example, it is now realized that the modeling process itself is valuable even if the resulting models are not immediately useful for management. The major thrust in the past has been water quality (eutrophication) modeling, but there has been a recent shift toward developing toxic substances models. Modelers and model users have been limited by a lack of knowledge of Great Lakes processes, limited data availability, and incomplete or improper validation. In the future, greater emphasis is needed on specifying prediction uncertainty and conducting proper model validation — including calibration, verification, and post-audits. Among the Great Lakes modeling activities likely to have the greatest payoff in the near future are (1) the development and refinement of toxic substances models, (2) post-auditing and improvement of eutrophication models, and (3) the adaption of models for use on personal computers to allow greater model utilization.     

WEAP21—A Demand-, Priority-, and Preference-Driven Water Planning Model

Abstract

The Water Evaluation and Planning Version 21 (WEAP21) Integrated Water Resource Management (IWRM) model seamlessly integrates water supplies generated through watershed-scale hydrologic processes with a water management model driven by water demands and environmental requirements and is governed by the natural watershed and physical network of reservoirs, canals, and diversions. This version (WEAP21) extends the previous WEAP model by introducing the concept of demand priorities and supply preferences, which are used in a linear programming heuristic to solve the water allocation problem as an alternative to multi-criteria weighting or rule-based logic approaches. WEAP21 introduces a transparent set of model objects and procedures that can be used to analyze a full range of issues faced by water planners through a scenario-based approach. These issues include climate variability and change, watershed condition, anticipated demands, ecosystem needs, the regulatory environment, operational objectives, and available infrastructure.     

Drivers of groundwater use and technical efficiency of groundwater,canal water,and conjunctive use in Pakistan’s Indus Basin Irrigation System

Abstract

This paper explores the major determinants of heavy reliance on groundwater and the extent to which conjunctive use of ground and surface water affects the production efficiency of Pakistan’s irrigators. The results show that the major drivers of groundwater use in Pakistan’s agriculture are the variability and uncertainty associated with surface water delivery and that any effort to address the groundwater–energy nexus challenge should first consider fixing the problems associated with surface water supplies. The findings also suggest that having access to groundwater does not directly translate into improvements in technical efficiency of production.     

Reproductive Potential and Fecundity of Lake Trout Strains in Southern and Eastern Waters of Lake Ontario, 1977–1994

We assessed the reproductive potential of various genetic strains of hatchery lake trout (Salvelinus namaycush) in southern and eastern Lake Ontario from indices of fecundity and indices of male abundance. Indices were constructed from catches of mature lake trout in gill nets during September 1980 to 1994 after correcting for mortality from sea lampreys (Petromyzon marinus) which occurred between September sampling and late fall spawning. Strain and age were assigned to individual lake trout based on clipped fins and maxillary bones or coded wire tags. Fecundity-length relationships for fish of the same age, determined from mature females collected in 1977 to 1981 and 1994, were not different (P > 0.05) among genetic strains. For all strains combined, fecundity-length relationships in 1977 to 1981 were not different among fish of various ages but in 1994, age-5 and -6 fish had fewer eggs (P < 0.003) than age-7 fish, and age-7 fish had fewer eggs (P < 0.003) than fish of age 8, 9, or 10. Annual indices of fecundity varied 19 fold and indices of mature males varied 11 fold; both indices were low in the early 1980s, increased sharply in the mid 1980s, and peaked in 1993. The strain which dominated fecundity and mature male indices shifted during the study from Seneca Lake strain to Lake Superior strain and then back to Seneca Lake strain. However, changes in either reproductive potential or genotypes do not appear responsible for the abrupt appearance of naturally-produced yearling lake trout throughout southern and eastern Lake Ontario in 1994–1995, the first widespread occurrence of juveniles produced by hatchery lake trout in Lake Ontario.     

Contamination and toxicity trends for sediments — Case of the Elbe river

The paper deals with sediment studies in the Upper and Middle Elbe between 1991 and 1996. Hydrological and seasonal factors are discussed with respect to trends in sediment contamination. An investigation programme is described including periodical measurements of inorganic and organic pollutants at monitoring stations as well as in-depth case studies. In these studies reference sites represent background conditions. Heavily contaminated reaches are taken as the worst case scenario. An integrated approach is applied combining chemical and ecotoxicological investigations. Factors are defined which must be taken into account in order to draw reliable conclusions for sediment quality. Contamination trends and trends in sediment toxicity are derived for the river Elbe.     

Concentrations and loads of nutrients and major ions in the Niagara River, 1975–2018

Environment and Climate Change Canada has monitored Niagara River water quality in support of the Great Lakes Water Quality Agreement since establishing a fixed site at Niagara-on-the-Lake in 1975. Using over 40 years of data from this site along with the Fort Erie location added in 1983, we examine the status and trends of concentrations and loadings of nutrients and major ions and assess evidence of sources between the two stations. Trends were observed for the majority of measured parameters and there is strong agreement between trends in concentrations and loadings which are generally higher at the downstream site; however, upstream/downstream differences indicate relatively little loading occurs along the length of the river itself. For total phosphorus (TP), inputs from Lake Erie via the Niagara River account for the majority of loading to Lake Ontario and, in some years, exceed the 7000 MTA Lake Ontario target. Between 2014 and 2018, we calculate the mean Niagara River TP loading to be 5275 MTA. We highlight the major changes in water quality constituents over time, including TP, and reveal increased seasonal consumption of TP and SiO₂, reflecting potential increases in the biological productivity in Lake Erie. The long and rich Niagara River dataset, which comprises year round sampling (including rare winter data), provides detailed tracking of changing Great Lakes water quality and could be further utilized to assess the impacts of climate change, improve understanding of diatom and harmful algal bloom dynamics, and enhance knowledge of in-lake major ion and nutrient dynamics.     

Operation and control of wastewater treatment — A Scandinavian perspective over 20 years

This paper aims to review the development of wastewater treatment operation and control over the last two decades. Due to the authors' background and experiences there is a special emphasis on the Scandinavian perspective. Since the developments in these countries have been in the forefront in the wastewater treatment area we believe that it may give a reasonable view of the progress also in other countries. The results of regulatory, technical and economical driving forces are discussed. A brief historical review of the progress of nutrient removal is made, and current methodologies for the operation and control of nutrient removal systems is reviewed.     

Delineation of Groundwater Potential Zones in Arid Region of India—A Remote Sensing and GIS Approach

The present research is an attempt to find out the groundwater potential zones within an arid region of India supported by the scientific investigation of lithology, geomorphology, geohydrological characterization of geological formations and their interrelationship. Thematic layers of drainage, lithology, geomorphology, lineaments, slope, soil, digital elevation model, rainfall, landuse/land cover and well inventory have been generated by using ancillary data, digital satellite image, water level data of 90 observation wells for last 11?years (2000?C2010), litholog data along with ground truthing. The groundwater potential zones have been classified into five categories like very poor, poor, moderate, good and excellent. The potential zones were obtained by weighted overlay combination using the spatial analyst tool in ArcGIS 9.2. During weighted overlay analysis, the ranking was given for each individual parameter of each thematic map and weights were assigned according to their influence such as lithology (20?%), geomorphology (15?%), lineament density (15?%), drainage density (15?%), soil (10?%), slope (10?%), rainfall (5?%), land use and land cover (5?%) and digital elevation model (DEM) (5?%) and it was found that the potential zones in terms of very poor, poor, moderate, good and excellent zones covered 13.7?%, 42.8?%, 27.3?%, 10.8% and 5.4% respectively of the total area. The result also has been validated by yield data collected from existing sources and it confirms that the higher yield categories are falling within excellent groundwater potential zones where yield ranges from 23 to 40.3?l/s and lower values ranging from 8.1 to 10.6?l/s are falling within poor groundwater potential zones.     

Opening Speech from The Department of International Cooperation, Science ＆ Technology, MWR——For 2006 Cambodian officials＇ Seminars

Distinguished guests, ladies and gentlemen, Good morning! Pleased to know that 2006 Seminars on ＂Water Resources Planning ＆ Management＂ and ＂Power System Planning ＆ Analysis＂ are being held for Cambodia today, and the Department of International Cooperation, Science and Technology under the Ministry of Water Resources would like to extend its congratulations,     

Development and Analytical Verification of an Integrated 2-D Surface Water—Groundwater Model

DIVAST is a two-dimensional hydrodynamic and water quality numerical model developed for estuarine and coastal modelling. The original model enables the simulation of problems such as pollution and flooding in surface waters. In this paper the existing model is extended to allow the modelling of 2-D groundwater as well as surface water in the same model, using an integrated approach rather than two disparate models. The changes to the original model are summarised and the method of implementation is outlined. The new extended model (DIVAST-SG) is then tested against an analytical solution to verify that the model solves the equations correctly. The model is shown to predict the analytical solution for two different scenarios to within approximately 1 % of the height of flood wave.     

What controls distribution of larval and juvenile yellow perch? The role of habitat characteristics and spatial processes in a large,shallow lake

The goal of this study was to determine the relative contribution of environmental and spatial processes governing the distribution of larval and juvenile yellow perch (Perca flavescens) in two shallow embayments of a large fluvial lake on the St. Lawrence River system. We tested the hypotheses that: i) larval distribution is not related to habitat characteristics, presumably due to their relatively low swimming capacity, whereas ii) these environmental variables drive juvenile distribution, reflecting a more active habitat selection. This study is one of the first attempts to partition the relative roles of environmental and spatial factors in shaping the distribution of a freshwater fish through its early ontogeny. We show that larvae were not spatially aggregated within the embayments and that habitat characteristics, mainly related to aquatic vegetation, played an important role in explaining their distribution. In contrast, juvenile abundances were not significantly related to habitat characteristics, despite being spatially structured over multiple scales. Contrary to our predictions, habitat association was stronger for larvae than for juveniles which were aggregated independent of habitat characteristics. Increased swimming capacities may thus facilitate the aggregation of juveniles rather than strengthening their association with habitat, at least at the scales considered here (ca 3 km²). These results shed a new light on the factors governing larval and juvenile yellow perch distribution, suggesting that active habitat choice might begin earlier than previously thought.     

Occurrence and distribution of organochlorine pesticides and polycyclic aromatic hydrocarbons in surface sediments from Qinghai Lake,northeast Qinghai–Tibet plateau,China

Organochlorine pesticides (OCPs) and polycyclic aromiatic hydrocarbons (PAHs) were analyzed in surface sediment samples collected from Qinghai Lake, the largest lake in China, which is situated in the northeast Qinghai–Tibet plateau at an altitude of 3200 m. The concentrations of these pollutants ranged from 0.02 to 1.00 ng/g for hexachlorocyclohexanes (HCHs), from not detected to 0.86 ng/g for dichlorodiphenyltrichloroethanes (DDTs), from 0.26 to 1.73 ng/g for OCPs, and from 366 to 966 ng/g for PAHs. The predominance of α-HCH suggests that long-range atmospheric transport is an important source for HCHs. A low α- to γ-HCH ratio (3.87 on average) indicates the possible usage of lindane in the drainage basin. The high percentage of p,p′-DDE and p,p′-DDD and the low percentage of o,p′-DDT indicated significant degradation from previous inputs, and no recent inputs of dicofol derived DDT. Based on the analysis of the component ratios, PAHs were found to be primarily from the combustion of biomass and coal-based fossil fuels. Using the Canadian sediment guidelines, PAHs are of greater ecological concern than OCPs in Qinghai Lake.     

Spatial and temporal distributions of lake whitefish spawning stocks in Northern lakes Michigan and Huron, 2003–2008

Adult lake whitefish were tagged and released from the Big Bay de Noc (BBN) and Naubinway (NAB) stocks in northern Lake Michigan, and the Detour (DET) and Cheboygan (CHB) stocks in northern Lake Huron during 2003–2006 to describe their spatial and temporal distributions. The contemporary spatial distributions were compared with past distributions of the BBN and NAB stocks. Sixty-two percent of BBN tag recoveries occurred in Wisconsin waters during winter, spring and summer, but 83% of fall tag recoveries were made near the tagging site. Eighty-eight percent of the NAB tag recoveries were made in the management unit of tagging and 7% occurred into northern Lake Huron. Over 90% of the DET stock remained in the vicinity of the tagging sites regardless of the season, while 75% of the CHB tag recoveries were made in northwestern Lake Huron and 17% were made in Ontario. Based on regression tree analysis, there were strong stock, season, and year effects on movement distances, with weaker effects due to sex and length at tagging. Spatial distribution of the BBN stock changed from 1978–1982 to 2003–2008, but spatial distribution of the NAB stock did not. Substantial differences in movement and distribution existed among the four stocks, large seasonal differences in spatial distribution were found within some stocks, and lake whitefish exhibited strong spawning site fidelity. Present management unit boundaries are inappropriate for managing three of our four stocks, and agencies should consider developing single harvest limits for both northern Lake Huron and western Lake Michigan.