Deploy diverse renewables to save tropical rivers.

A strategic mix of solar, wind and storage technologies around river basins would be safer and cheaper than building large dams, argue Rafael J. P. Schmitt, Noah Kittner and colleagues

Socio-economic profiling of tropical rivers<br />

Summary of the reportTropical Rivers and Coastal Knowledge (TRaCK) consortium was established in 2007 under the&nbsp; Commonwealth Environment Research Facilities Programme with the aim of providing the science and knowledge that governments, communities and industries need for the sustainable use and management of Australia&rsquo;s tropical rivers and estuaries. This report has been written as a part of the Tropical Rivers and Coastal Knowledge (TRaCK) project 3.1, &ldquo;People and economy&rdquo;.Tropical rivers of Australia are defined as catchments stretching from Broome in Western Australia to Cape York in Queensland, draining into either the Timor Sea or Gulf of Carpentaria. Tropical rivers (TR) thus include 54 river catchments and cover an area of more than 1.3 million km2. Key characteristic of the tropical rivers, in general, is that their hydrology is determined&nbsp; by a short and distinct wet season, followed by longer dry season. While water might be abundant during the wet season, it is generally ephemeral and becomes scarce during the dry season.This document reports on four major objectives of stage (B) of the TRaCK project 3.1, &ldquo;People and economy&rdquo;. The four objectives were: (a) to develop an integrated conceptual framework for the socio-economic profiling; (b) to update existing knowledge with data from the 2006 Census; (c) to develop profiles of individual catchments based on their individual socio-economic characteristics;&nbsp; and (d) to compare and contrast the TR catchments and to identify catchments which are socio-economically &lsquo;similar&rsquo; or &lsquo;dissimilar&rsquo;.The conceptual framework developed for the study (objective a) was grounded in the social impact assessment theory but also reviewed literature from other related research areas, such as adaptive capacity, social resilience and institutional analysis. The original framework also included a &ldquo;wish list&rdquo; of variables that should ideally be populated in order to provide full profiles of&nbsp; socio-economic conditions across the north. The conceptual framework is presented in Section 2 of the report.The data collection and updating process (objective b) has identified several important data gaps, discussed further in Section 5.1 of the report. A comparison of the &ldquo;wish list&rdquo; of variables developed at the start of the project with the list of variables for which we were able to find recent, readily available secondary data, revealed some important data gaps. As a result, the&nbsp; conceptual framework originally proposed could not be populated to the full extent and was thus collapsed into the following five domains: (a) population / demographic characteristics; (b) economic parameters; (c) infrastructure and housing; (d) human and social capital, combining institutional arrangements with individual wellbeing; and (e) environment, heritage and land use. The data were used to create GIS-linked maps of socioeconomic characteristics of all catchments across the north (Section 3), as well as to create profiles of each individual catchment (objective c, presented in Section 4.1 and Appendix 2).Although the tropical rivers (TR) region represents around a quarter of the Australian land mass, it contains just two percent of the population. The region is characterised by disperse human settlement, with the only significant populations (more than 10,000 people) located in and around Darwin in the Northern Territory, Broome in Western Australia, and Mount Isa in Queensland. The&nbsp; Accessibility/ Remoteness Index of Australia (ARIA) indicates that large tracts of the TR region fall within the &ldquo;very remote&rdquo; category of ARIA as defined by ABS, with scores higher then 10.5.The percentage of people speaking a language other than English at home is relatively high in TR region. Most of the languages, other than English, which are spoken at home are Indigenous languages. And the percentage of the population speaking non-Indigenous languages at home is proportionally smaller (up to 15 percent per catchment) than populations speaking Indigenous languages at home (up to over 80 percent per catchment). For example, in Leichhardt River, only 74 percent of population was born in Australia, yet 82 percent speak only English at home. In contrast, the entire populations of both the Moyle and the Walker river catchments were born in Australia, yet only 12 and 10 percent, respectively, speak only English at home.About 42% of all homes in TR region have an internet connection, while 65% of all homes have a motor vehicle. In addition, catchments closer to urban regions such as Adelaide River (near Darwin) tend to have higher rates of internet connection and homes with registered motor vehicle (56% and 95% and, respectively), while more remote catchments tend to have a very low percentage of homes with internet connection (such as, for example, 20% in King Edward River or 11% in Fitzmaurice River) and a low percentage of homes with a registered motor vehicle (34% in King Edward River and 38% in Fitzmaurice). Similar disparity appears in human capital data. To use the same catchments as examples, less than one percent of people in the Adelaide catchment never attended school, while 3% of people in the Fitzmaurice and 5.5% of people in the Kind Edward catchment have never received any formal schooling.Combined government-provided services such as health, education, defence and public services were identified as the largest employer in the region, employing on average 25 percent of persons over 15 years of age in TR catchments in 2006. The second largest employment sector was agriculture and forestry, with an average of 11.5 percent across catchments, followed by mining, retail and construction, each employing around 4 percent of population over 15 years of age. Median weekly income per person varied greatly between catchments from around 150$per person per week in the Blyth and Koolatong catchments, to around 700$ per person per in mining-dominated catchments like the Leichhardt and Embley. The majority of the labour force in the catchments across the TR region was concentrated in the Darwin region. The few other catchments with larger settlements, such as Mt Isa, Broome and Katherine, dominate the remaining numbers of total labour available in the TR region and the labour force across the majority of other catchments is very limited suggesting that this might be one of the limiting factors for potential developments in the future.Basic infrastructure in the north is also limited. Transport infrastructure is limited to a weak network of all-weather sealed roads and airports, and very few ports. This is particularly true in the Kimberleys, Arnhem Land and Cape York Peninsula. Services are also limited to a few larger rural centres. For example, one third of 54 northern catchments profiled did not have any educational facilities. Similarly, the overwhelming majority of the community organizations across TR region registered in Australian Community Guide, 97 percent, were located within 10 catchments of the region.Much of the land in the TR region is in its natural condition, with most land use following within the categories of &lsquo;land under conservation&rsquo; &lsquo;traditional Indigenous use&rsquo;, and &lsquo;land under production from a relatively natural environment&rsquo; (such as grazing of natural vegetation). Other land uses, such as land under dryland agriculture, irrigated land and land under intensive uses, are minimal across the region. Great differences however do exist between the catchments. For example, all of the land in Goyder River catchment is classified as in natural condition (under traditional Indigenous use), while only 2.5% of land in Gilbert River is classified as being in natural condition (under conservation), with no land under traditional Indigenous use. The majority of land in Gilbert River catchment, more than 95%, is under grazing.To meet the last objective of this study, TR catchments were compared and contrasted in order to identify catchments which are socio-economically &lsquo;similar&rsquo; (and, by corollary, socio-economically &lsquo;dissimilar&rsquo;). It is important to note that, given the complexity of variation between the catchments, more good quality data is needed to reduce the uncertainty around the findings of this investigation. Nonetheless, distinct clusters of catchments have been identified and are discussed in Section 4.2 of the report.For example, Settlement Creek, Staaten, Keep, Gilbert, Holroyd and Norman rivers were grouped together as relatively similar. This cluster is characterised by relatively high levels of employment in agriculture and a high percentage of land under grazing. Mobility is also relatively high, with a large proportion of people owning their homes. A medium to high proportion of residents speak English only. Catchments in this cluster have low numbers of homes with no vehicles or no internet connection, and a relatively low percentage of people with no schooling. Household sizes and numbers of people per bedroom are also low, as well as the percentage of women with 3 children or more and the percentage of one parent families. The percentage of Aboriginal people in those catchments is low to relatively low.Another cluster identified in the analyses comprised of the Jardine, King Edward, Coleman and Watson rivers and Bathurst and Melville Islands. This cluster is characterised by a low mobility of population, low incomes and low employment in agriculture, manufacturing or mining. Employment by government is higher. In these catchments a low percentage of people are purchasing their homes, while most families are renting homes from the community organisations. An increased proportion of the population has no schooling. Catchments in this cluster also have medium to relatively high numbers of homes with no vehicles and no internet connection, and a relatively high proportion of women with 3 children or more. Household sizes and numbers of people per bedroom are higher than in the previous clusters described. The percentages of Aboriginal people in these catchments are medium to high, however, the percentage of land under Indigenous traditional use is not very high (except at Bathurst and Melville islands).In summary, the socio-economic profiling identified considerable differences both between and within the catchments in the north. Biophysical and cultural differences, as well as differences in human, social and institutional capital and available infrastructure, will play a large role in determining both the opportunities for development (mining, agriculture, tourism) as well as capacities of the communities in those catchments to identify opportunities and take the advantage of the opportunities as they present themselves.This study summarised data that might be of help to other researchers and communities in the north engaged in development of sustainable use and management options for the tropical rivers. Furthermore, identification of different types of catchments, that are not necessarily geographically linked but are similar in socio-economic terms, might aid in development of the management approaches that are more targeted, and thus more appropriate, than &ldquo;one size fits all&rdquo; approach; yet require lesser effort than targeting of individual catchments. Potential of this approach to be used for improved understanding and management of natural resources issues in other rural and remote regions of Australia warrants further research. Research into development of catchment typologies based on entire sets of data, that is biophysical characteristics as well as socio-economic characteristics of the catchments, also warrants further research

Environmental Impact of a Tidal Bore on Tropical Rivers

A tidal bore impacts significantly on the estuarine ecosystem, although little is known on the flow field, mixing and sediment motion beneath tidal bores. In the absence of detailed field measurements, a quasi steady flow analogy was applied to investigate an undular tidal bore with inflow Froude numbers 1.6 and 1.25. Experimental results indicated that rapid flow redistributions occur beneath the free-surface undulations, with significant variations in bed shear stress between wave crests and troughs. Dynamic similarity was used to predict detailed flow characteristics of tidal bores with inflow Froude number between 1.3 and 1.6. The effects of periodic loading on river sediments, scour of the riverbed and flow mixing behind the bore were investigated. A better understanding of these processes will contribute to better management practices in tidal bore affected rivers, including the Styx, Daly and Ord rivers in tropical Australia

Environmental Impact of Undular Tidal Bores in Tropical Rivers

A tidal bore impacts significantly on the estuarine ecosystem, although little is known on the flow field, mixing and sediment motion beneath tidal bores. In the absence of detailed systematic field measurements, a quasi-steady flow analogy was applied to investigate undular tidal bores with inflow Froude numbers between 1.25 and 1.6. Experimental results indicated that rapid flow redistributions occur beneath the free-surface undulations, with significant variations in bed shear stress between wave crests and troughs. Dynamic similarity was used to predict detailed flow characteristics of undular tidal bores. The effects of periodic loading on river sediments, scour of river bed and flow mixing behind the bore are discussed. A better understanding of these processes will contribute to better management practices in tidal bore affected rivers, including the Styx and Daly rivers in tropical Australia

Eco-morphodynamic carbon pumping by the largest rivers in the Neotropics

AbstractThe eco-morphodynamic activity of large tropical rivers in South and Central America is analyzed to quantify the carbon flux from riparian vegetation to inland waters. We carried out a multi-temporal analysis of satellite data for all the largest rivers in the Neotropics (i.e, width > 200 m) in the period 2000–2019, at 30 m spatial resolution. We developed a quantification of a highly efficient Carbon Pump mechanism. River morphodynamics is shown to drive carbon export from the riparian zone and to promote net primary production by an integrated process through floodplain rejuvenation and colonization. This pumping mechanism alone is shown to account for 8.9 million tons/year of carbon mobilization in these tropical rivers. We identify signatures of the fluvial eco-morphological activity that provide proxies for the carbon mobilization capability associated with river activity. We discuss river migration—carbon mobilization nexus and effects on the carbon intensity of planned hydroelectric dams in the Neotropics. We recommend that future carbon-oriented water policies on these rivers include a similar analysis

Use of stable isotopes, organic and inorganic chemistry to identify pollution sources and weathering processes in two small tropical rivers in southwestern India

The two main objectives of this study were to assess pollution dynamic from organic and inorganic major ion chemistry and stable isotopes (δ15N and δ18O) and to determine the weathering processes using carbon isotopes in two tropical river basins, i.e. Nethravati and Swarna, along southwest coast of India. These short length river basins (around 100 km) are characterized by high annual rainfall, warm temperature, high runo" (~3300mm) draining Precambrian basement rocks composed of green-stones, granitic-gneiss, charnockite and meta sediments. Intense silicate weathering is induced by high runo" and warm temperature (Gurumurthy et al., 2012). In this study, stable isotopes (δ15N & δ18O)of organic molecules from sewage and agricultural effluents,and carbon isotopes (δ13C) of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were measured to trace agricultural and domestic pollution and to identify the sources of inorganic carbon and the nature of chemical weathering in these river basins. Carbon isotopes measured on DIC reveals sources of carbon into the river, such as carbonate/silicate weathering of rocks, mineralization of organic matter from C3/C4 plants, soil and atmospheric CO2. The nitrate and phosphate levels remain low, with values ranging from 5 to 9 μM, and 0 to 2 μM respectively. The δ13C DIC values range from =-9.03 +/- 0.99 for the Swarna basin to -8.08 +/-0.78 for the Nethravati basin. These values point to a mixing of carbonate and silicate weathering products with a dominance of C3 vegetation, prevalent in the Western Ghats. The DOC values for both river basins are very low and very close: 0.72 +/- 0.09 mg/L (Swarna river) and 0.62 +/-0.11 mg/L (Nethravati river). This indicates that the contributions of organic matter from the adjacent forests and the $ood plains are very low during the sampling period. The analysis of organic acids reveals low amount of Oxalate and Acetate, and trace of Malate and Tartaric acids. The dissolved and particulate organic carbon (DOC and POC) concentrations are very low in these two rivers. During the dry season, river discharge is mainly supplied by groundwater with generally low contents in dissolved and particulate fractions. Even if we observe low concentration, we measured higher DOC and POC in the Swarna river. These higher DOC concentrations are accompanied with lower SUVA value. This indicates that more labile DOC (less aromaticity) is exported within this basin during dry season. C/N values in POC also show that the organic carbon is “fresher” and is probably more autochtonous than in the Nethravati river. Indeed, C/N value are closer of an autochthonous production (C/N : 2-6) than allochthonous one (C/N: 8-20). These observations can be explained as the Svarna watershed land use is more agricultural than in Nethravati. Agricultural lands generally export signi%cant amount of nutrients to rivers and participate to enhance autochthonous productivity. Autochthonous organic carbon production is more labile and less aromatic

Patents and Competition in the Automobile Industry

Methane (CH4) fluxes from world rivers are still poorly constrained, with measurements restricted mainly to temperate climates. Additional river flux measurements, including spatio-temporal studies, are important to refine extrapolations. Here we assess the spatio-temporal variability of CH4 fluxes from the Amazon and its main tributaries, the Negro, Solimoes, Madeira, Tapajos, Xingu, and Para Rivers, based on direct measurements using floating chambers. Sixteen of 34 sites were measured during low and high water seasons. Significant differences were observed within sites in the same river and among different rivers, types of rivers, and seasons. Ebullition contributed to more than 50% of total emissions for some rivers. Considering only river channels, our data indicate that large rivers in the Amazon Basin release between 0.40 and 0.58 Tg CH4 yr(-1). Thus, our estimates of CH4 flux from all tropical rivers and rivers globally were, respectively, 19-51% to 31-84% higher than previous estimates, with large rivers of the Amazon accounting for 22-28% of global river CH4 emissions.Funding Agencies|FAPESP [08/58089-9, 2011/06609-1, 2011/14502-2, 2012/17359-9]</p

Habitat and community structure modulate fish interactions in a neotropical clearwater river

Species interactions can modulate the diversity and enhance the stability of biological communities in aquatic ecosystems. Despite previous efforts to describe fish interactions in tropical rivers, the role of habitat characteristics, community structure, and trophic traits over these interactions is still poorly understood. To investigate among-habitat variation in substratum feeding pressure and agonistic interactions between fishes, we used remote underwater videos in three habitats of a clearwater river in the Central Western, Brazil. We also performed visual surveys to estimate the abundance and biomass of fishes and proposed a trophic classification to understand how these variables can affect fish interactions. Community structure was the main factor affecting the variation in the interactions among the habitats. Biomass was the main variable determining which habitat a fish will feed on, while species abundance determined with how many other species it will interact in the agonistic interaction networks for each habitat. Specific habitats are not only occupied, but also used in distinct ways by the fish community. Overall, our results demonstrate the importance of the heterogeneity of habitats in tropical rivers for the interactions performed by the fishes and how the intensity of these interactions is affected by community structure