Satellites at work (Space in the seventies)

The use of satellites in the areas of communications, meteorology, geodesy, navigation, air traffic control, and earth resources technology is discussed. NASA contributions to various programs are reviewed

A quantitative risk assessment of waterborne infectious disease in the inundation area of a tropical monsoon region

Flooding and inundation are annual events that occur during the rainy season in Cambodia, and inundation has a strong relationship with human health. This study simulated the coliform bacteria distribution using a hydraulic model and estimated the impact of inundation on public health using a dose–response model. The model parameters were calibrated using field survey data from Cambodia and obtained good agreement with the coliform group count distribution. The results suggest that the impact of inundation on human health is most noticeable in residential areas. The annual average risk of infection during medium-sized flood events is 0.21. The risk due to groundwater use ranges from 0.12 to 0.17 in inundation areas and reaches as high as 0.23 outside the inundation areas. The risk attributed to groundwater use is therefore higher than that for surface water use (0.02–0.06), except in densely populated areas at the city center. There is a high risk for infection with waterborne disease in residential areas, and the annual average risk during small flood events is 0.94. An assessment of possible countermeasures to reduce the risk shows that the control of inundation may bring more risk to public health in Cambodia. Shallower inundation water (<0.3 m) leads to a higher risk of infection, but if the depth is greater than 2 m, the risk is low in residential areas.The simulated results explain the spatial distributions of infection risk, which are vitally important for determining the highest priority places with relatively high risk and will be helpful for decision makers when considering the implementation of countermeasures

A new modified spatial approach for monitoring non-perennial river water availability using remote sensing in the Tankwa Karoo, Western Cape, South Africa

Non-perennial rivers (N-PRs) make up two thirds of all rivers in South Africa, yet many are ungauged. Traditionally, it has been assumed that when a flow is recorded, there is water throughout that river. These assumptions have led to incorrect estimations of available water resources. This work thus aimed at developing a new spatially explicit framework, for monitoring river water availability in a N-PR system. The Tankwa River in South Africa was used for testing this approach. The length of the river reach with water was determined using the Sentinel-1 and Sentinel-2 data derived indices. Image thresholding was applied to Sentinel-1, and the normalised difference water index (NDWI) to Sentinel-2. Sentinel-2 yielded an overall accuracy (OA) of 85%, whereas Sentinel-1 yielded an OA of 38%. The analysed reach of the Tankwa River had an actual length of 9 244 m. Based on the performance of Sentinel-2 data, further analysis was undertaken using Sentinel images acquired during the months of February, May and July of 2016. The results indicated that the lengths of the reaches of inundated Tankwa River were 2 809 m, 3 202 m and 2 890 m, respectively. Overall, the findings of this study show that an estimated length of a river inundated by water can be determined using new-generation Sentinel data and these results provide new insights on the dynamics of N-PRs – a previously challenging task with broadband multispectral satellite datasets

Blue harvest: inland fisheries as an ecosystem service

Global food production has increased greatly in recent years and rural livelihoods are much improved in many regions. Yet, despite this clear progress rural poverty and food insecurity remain deeply entrenched in many areas, especially in South Asia and sub-Saharan Africa. In response the international community has renewed calls for increased commitment to meeting the needs of the world's poor. This report, commissioned as a contribution to the 10th Conference of the Parties to the Convention on Biological Diversity taking place in Nagoya, Japan, not only underlines the value of freshwater fisheries but provides guidance on how the ecosystem approach can be applied in order to sustain future harvests.Inland fisheries, Nutrition, Food security, Sustainability, Ecosystems

Diverse migration tactics of fishes within the large tropical Mekong River system

Fish often migrate to feed, reproduce and seek refuge from predators and prevailing environmental conditions. As a result, migration tactics often vary among species based on a diversity of life history needs, although variation within species is increasingly being recognised as important to population resilience. In this study, within- and among-species diversity in life history migratory tactics of six Mekong fish genera was examined using otolith microchemistry to explore diadromous and potamodromous traits. Two species were catadromous and one species was an estuarine resident, while the remaining three species were facultative in their migration strategies, with up to four tactics within a single species. Migrant and resident contingents co-existed within the same species. Management, conservation and mitigation strategies that maintain connectivity in large tropical rivers, such as effective fishway design, should consider a diversity of migration tactics at the individual level for improved outcomes

Land use, urban, environmental, and cartographic applications, chapter 2, part D

Microwave data and its use in effective state, regional, and national land use planning are dealt with. Special attention was given to monitoring land use change, especially dynamic components, and the interaction between land use and dynamic features of the environment. Disaster and environmental monitoring are also discussed

Improved land management in the Lake Victoria Basin: Linking land and lake, research and extension, catchment and lake basin

Lake Victoria is of immense economic and environmental importance in the eastern and central African region. The lake is the largest freshwater body in the tropics and its basin supports one of the densest and poorest rural populations in the world. About 21 million people rely primarily on subsistence agricultural and pastoral production for their livelihoods. But pervasive poverty has hindered sustainable use of the land resources and there has already been considerable land degradation. There is little doubt that sedimentation and nutrient run-off, urban and industrial point source pollution and biomass burning, have induced the rapid eutrophication of Lake Victoria over the last fifty years. Invasion of water hyacinth and loss of endemic biodiversity are interrelated and compound problems for the lake environment and the welfare of its people. This project set out to assess the extent and causes of processes that contribute to pollution of the lake and to localize interventions for more sustainable land management. In a one year start-up phase, emphasis was placed on prioritizing river basins and assessing the land degradation problems in relation to nutrient and sediment inputs to the lake. This document summarizes progress on the proposed activities and the principal findings achieved under the start-up phase. The detailed results supporting these findings are given as an annex. A regional assessment identified the Nyando River Basin as a major source of sediment and phosphorus flow into Lake Victoria, and so much of the initial work was concentrated on this river basin while methods were being refined. The study identified severe soil erosion and land degradation problems throughout the Nyando river basin. Accelerated run-off and sheet erosion over much of the iii catchment area has led to severe rill, gully and stream bank erosion in lower parts of the river basin. The principal causes of erosion include deforestation of headwaters and overuse of extensive areas of fragile lands on both hillslopes and plains, coupled with loss of watershed filtering functions through encroachment on wetlands and loss of riverine vegetation. Associated with soil erosion, there has been substantial depletion of soil quality over much of the basin. Communities in the river basin are aware and concerned about water shortages and local land degradation but there is a low level awareness of the off-site effects. The lower parts of the river basin and the lake are particularly vulnerable to the return of a large rainfall event, such as experienced in the early 1960’s, which would cause catastrophic damage. The report outlines possible broad areas of intervention. The major requirements are to: (1) rapidly reduce pressure on vegetation cover over large areas of fragile land, including headwaters, shallow soils on hillslopes, and fragile soils on plains and the Nyando escarpment, (2) restore the filtering function of wetlands and riverine buffer strips, and (3) increase productivity of agricultural land that has high potential, particularly by removal of soil phosphorus and other soil nutrient constraints, which will help reduce pressure on fragile lands. The current catchment extension approach of the Soil and Water Conservation Branch has received considerable penetration in terms of number of participating farmers, but the efforts are unlikely to have significant impact on sediment and nutrient transfers to the lake. The Branch has had most impact in high population density areas largely within cash cropping systems. In contrast, it is in the marginal areas with extensive agropastoral systems that erosion risk is high. These are mostly communally-used grazing lands and government trust land where population density is fairly low and there is little incentive for investment in soil conservation. Complimentary approaches based on integrated watershed management are needed that jointly consider agricultural areas, forest areas and trust land, with highly active community participation. The emphasis must be on large area management of fragile lands and buffer zones around riparian zones, wetlands, and headwater catchment areas. Given the high cost of rehabilitation of marginal areas, priority should be given to assessment of their natural regeneration potential, in conjunction with policy and institutional innovation for their improved management. The project has been a focal point for the development of some exciting new methods for the quantitative assessment of land management problems that are of international significance. New remote sensing and ground survey tools were developed for rapid assessment of land and soil degradation and for precise spatial management of soils and vegetation. For example, critical target levels of dry season herbaceous vegetation cover depending on soil type and slope can be mapped. Progress towards achieving targets for buffer zone vegetation management can also be monitored. These tools are ready for deployment in the Nyando and other river basins

New 3-d video methods reveal novel territorial drift-feeding behaviors that help explain environmental correlates of Chena River chinook salmon productivity

Thesis (Ph.D.) University of Alaska Fairbanks, 2014.Chinook salmon (Oncorhynchus tshawytscha) are critical to subsistence and commerce in the Yukon River basin, but several recent years of low abundance have forced devastating fishery closures and raised urgent questions about causes of the decline. The Chena River subpopulation in interior Alaska has experienced a decline similar to that of the broader population. To evaluate possible factors affecting Chena River Chinook salmon productivity, I analyzed both population data and the behavior of individual fish during the summer they spend as fry drift feeding in the river. Using a stereo pair of high definition video cameras, I recorded the fine-scale behavior of schools of juvenile Chinook salmon associated with woody debris along the margins of the Chena River. I developed a software program called VidSync that recorded 3-D measurements with sub-millimeter accuracy and provided a streamlined workflow for the measurement of several thousand 3-D points of behavioral data (Chapter 1). Juvenile Chinook salmon spent 91% of their foraging attempts investigating and rejecting debris rather than capturing prey, which affects their energy intake rate and makes foraging attempt rate an unreliable indicator of foraging success (Chapter 2). Even though Chinook salmon were schooling, some were highly territorial within their 3-D school configurations, and many others maintained exclusive space-use behaviors consistent with the population regulatory effects of territoriality observed in other salmonids (Chapter 3). Finally, a twenty-year population time series from the Chena River and neighboring Salcha River contained evidence for negative density dependence and a strong negative effect of sustained high summer stream discharge on productivity (Chapter 4). The observed territoriality may explain the population's density dependence, and the effect of debris on foraging efficiency represents one of many potential mechanisms behind the negative effect of high stream discharge. In combination, these findings contribute to a statistically and mechanistically plausible explanation for the recent decline in Chena River Chinook salmon. If they are, in fact, major causes of the decline (other causes cannot be ruled out), then we can be tentatively hopeful that the population may be experiencing a natural lull in abundance from which a recovery is possible.General Introduction -- Chapter 1: Measuring fish and their habitats: Versatile 2-D and 3-D video techniques with user-friendly software -- Chapter 2: Mechanisms of drift-feeding behavior in juvenile Chinook salmon and the role of inedible debris in a clear-water Alaskan Stream -- Chapter 3: Territoriality within schools: dynamic competition of drift-feeding juvenile Chinook salmon in 3-dimensional space -- Chapter 4: Low productivity of Chinook salmon strongly correlates with high summer stream discharge in two Alaskan rivers in the Yukon drainage

Bilateral Asymmetry in Asterisci Otoliths of Cyprinion kais and C. macrostomum (Cypriniformes, Cyprinidae) collected from Tigris River, Şirnak Region, Türkiye

Otolith traits such as size and mass were investigated in 60 fish specimens of C. kais and C. macrostomum collected from the Tigris River, Şırnak region, Türkiye collected from September 2015 to December 2015. The purpose of this work was to determine the asymmetry level in the otolith length (OL), otolith width (OW), and otolith mass (OM). OL's rate of asymmetry was greater than OW’s and OM's. The asymmetry in the three otolith traits rose with the fish length. The plausible reason for asymmetry in the otolith features explored has been considered relative to the inconsistency of growth triggered by ecological influence associated with the inconsistency in water temperature, salinity, depth, and contaminants occurring in the Tigris River System

Assessment and diversity of fish communities in non-wadeable tributaries of the Missouri and Mississippi rivers

As the geographical centers of riverscapes, rivers support fish populations at local and basin-wide scales. However, refinements to fish sampling protocols and theories underpinning basin-wide community ecology have been slowed by the inherent complexity and immensity of rivers. I conducted three extensive studies in non-wadeable tributaries of the lower Missouri and middle Mississippi rivers (Missouri, USA) to illuminate processes structuring riverine fish communities. In Chapter 2, I tested the efficacy of a six-gear fish community sampling protocol by repeatedly sampling nine sites in spring, summer, and fall (N = 36 surveys). I identified an efficient four-gear sub protocol that consistently detected 90% of observed species richness at sites and only required 52% of initial survey effort. In comparison, an electrofishing-only protocol detected lower percentages of fish richness, varied seasonally between summer and fall, and was nearly twice as variable. In Chapters 3 and 4, I contrasted fish communities inhabiting the Grand (10 sites, prairie region) and Meramec (12 sites, Ozark region) river systems. Chapter 3 examined tributary use by large-river specialist fishes (LRS), a guild of fishes that likely disperse into tributaries from the Missouri (Grand R.) and Mississippi (Meramec R.) rivers. I tested whether mean annual discharge consistently structured richness of LRS fishes at sites ([alpha] richness) within tributaries, and if habitat and downriver connectivity to the Missouri and Mississippi rivers explained additional variation in LRS [alpha] richness. Although species-discharge relationships were positive, discharge effect sizes varied between rivers revealing discharge did not consistently structure LRS [alpha] richness. After accounting for river-specific effects of discharge, downriver connectivity explained residual variation in LRS [alpha] richness, indicating dispersal into tributaries likely structured LRS [alpha] richness. Consequently, LRS [alpha] richness solely estimated from discharge might be underestimated in connected network branches and overestimated in isolated mainstem reaches. Chapter 4 expanded the research scope beyond LRS species to test whether regional connectivity (distance to dispersal source) or site-level habitat diversity (multivariate dispersion of nine habitat variables) explained α richness of three stream size guilds at sites: LRS species, headwater species likely sourced from [less than or equal to]3rd Strahler order streams, and core riverine fishes. In both river systems, downriver connectivity (distance upriver from mouth of mainstem river) and habitat diversity positively related to LRS- (R2 = 0.44 in Grand R, 0.91 in Meramec R.) and core-species (R2 = 0.37 in Grand R., 0.57 in Meramec R.) richness, respectively. Headwaters within 25 km of sites positively related to headwater species richness in the Grand River system (R2 = 0.85), but not in the Meramec River system where headwater richness was better explained by an inverse relationship with discharge (R2 = 0.32). Increasing LRS richness (13–17 spp.) downriver caused sites supporting the highest total species richness ([greater than or equal to]75th percentiles) to skew towards lower-midcourse reaches, rather than in midcourses where core-species richness and habitat diversity peaked. Because riverine fish richness manifests from regional dispersal and local habitat diversity, conserving areas of high richness will likely require management actions aimed at local and regional scales. Altogether these studies collecting 146 species and 145,147 individuals revealed non-wadeable tributaries are key riverscape elements that provide diverse riverine habitats and corridors for members of multiple regional fish species pools.Includes bibliographical reference