Sums, Products and Ratios for Crovelli’s Bivariate Gamma Distribution

Bivariate gamma distributions have been used successfully on modeling hydrological processes. In this work, supposing that X and Y follow the Crovelli’s bivariate gamma model, we deduce the exact distributions of the functions U?=?X?+?Y, P?=?XY and Q?=?X/(X?+?Y), as well as their respective moments. Those functions are important hidrological variables. A MAPLE code to compute the quantiles is provided. An application of the results is provided to rainfall data from Passo Fundo.     

Streamflow Variations in Monthly,Seasonal, Annual and Extreme Values Using Mann-Kendall,Spearmen’s Rho and Innovative Trend Analysis

Water Resources Management - The present study investigates the variations in the monthly, seasonal and annual streamflow timeseries at twenty (20) stations over the upper Indus river basin (UIRB)...     

Advancing Africa’s Great Lakes research and academic potential: Answering the call for harmonized,long-term,collaborative networks and partnerships

The African Great Lakes (AGL) have rich fisheries and are renowned “biodiversity hotspots”. Consequently the AGL and the ecosystem services they provide, underpin the welfare and livelihoods of over 50 million people across 10 countries. Despite the recognized importance of the AGL, these vital ecosystems and their livelihood support systems are threatened by numerous anthropogenic stressors at local, regional, and global scales. Past and continued efforts to address critical challenges on these lakes are often short-term, parochial, disparate, and uncoordinated resulting in a lack of comprehensive and comparable scientific data and inadequate resources to influence evidence-based policy. Over the past two decades, several international workshops, conferences and scientific publications have identified the need for collaboration, knowledge sharing, and harmonization of research and management as key elements to enhance conservation efforts in the AGL. In this commentary, we introduce the African Center for Aquatic Research and Education (ACARE), which aims to strengthen research and provide the scientific evidence needed to make informed decisions related to sustainable fisheries and aquatic resource management in the AGL. To do this, ACARE will administer a highly collaborative network of experts with three long-term goals: (1) strengthen global and regional research partnerships; (2) establish transboundary and inter-jurisdictional lake advisory groups; and (3) build capacity of freshwater scientists through experiential education and public engagement.     

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.     

JICA’s policies,experiences and lessons learned on impacts of urban floods in Asia*

This article describes the assistance policies of the Japan International Cooperation Agency in line with the international trend in disaster risk reduction. Through domestic experience, Japan has learnt that disaster risk reduction through structural measures and scientific and evidence-based assessment is indispensable for resilience, poverty reduction and sustainable development. Risk literacy, redundancy and continuous adaptation to situational changes are also important. In case studies of internationally known floods in Manila (2009) and Bangkok (2011), JICA gained confidence that its assistance policies are valid. The knowledge and experience of Japan and JICA have led the evolving global trend in disaster risk reduction.     

Unsafe water,sanitation and hygiene in Nigeria’s public spaces: the political economy angle

Water, sanitation and hygiene (WaSH) services in public spaces are examined from the political economy perspective in Nigeria. Through field observations and interviews, the study observed that WaSH practices at public spaces are less than optimal on account of poor or outright absence of necessary WaSH infrastructure and weak or non-existent regulation and enforcement of necessary standards, among other challenges. Socio-economic factors related to the category of users and the proprietary interests of specific spaces largely accounted for WaSH services inequality. It is argued that the failure of the state to guarantee functional WaSH infrastructure and enforce standard practices opens space for differentiated practices and standards consistent with specific interests.     

Comparison of M5 Model Tree and Artificial Neural Network’s Methodologies in Modelling Daily Reference Evapotranspiration from NOAA Satellite Images

The objective of this study was to compare feed-forward artificial neural network (ANN) and M5 model tree for estimating reference evapotranspiration (ET₀) only on the basis of the remote sensing based surface temperature (T_s) data. The input variables for these models were the daytime surface temperature at the cold pixel obtained from the AVHRR/NOAA sensor and extraterrestrial radiation (R_a). The study has been carried out in five irrigated units that cultivate sugar cane, which located in the Khuzestan plain in the southwest of Iran. A total of 663 images of NOAA–AVHRR level 1b during the period 1999–2009, covering the area of this study were collected from the Satellite Active Archive of NOAA. The FAO-56 Penman–Monteith model was used as a reference model for assessing the performance of the two above approaches. The study demonstrated that modelling of ET₀ through the use of M5 model tree gave better estimates than the ANN technique. However, differences with the ANN model are small. Root mean square error and R² for the comparison between reference and estimated ET₀ for the tested data set using the proposed M5 model are 13.7 % and 0.96, respectively. For the ANN model these values are 14.3 % and 0.95, respectively.     

扩展GM(1,M)模型混沌优化及其在边坡监测中的应用

基于GM(1,1)与常规GM(1,M)模型缺陷的分析,给出了扩展GM(1,M)模型(E-GM)及其响应递推式,进而指出了背景值生成因子的双重约束特性。扩展模型采用最新历史数据作为响应值初始条件,并提出以模型精度与法矩阵病态程度为准则引入混沌优化方法搜索最佳生成因子。工程实例计算表明,扩展模型预测精度及可靠性优于GM(1,1)及常规GM(1,M)模型。     

Identification of nitrate sources in Taihu Lake and its major inflow rivers in China, using δ(15)N-NO(3)(-) and δ(18)O-NO(3)(-) values

In the present study, δ(15)N and δ(18)O-NO(3)(-) values, as well as concentrations of some major ion tracers were determined in seasonal water samples from Taihu Lake and major watersheds to investigate the temporal and spatial variations of nitrate sources and assess the underlying nitrogen (N) biogeochemistry process. The results lead to the conclusion that the nitrate concentrations in Taihu Lake are lower in summer than that in winter due to the dilution effect of wet deposition. In winter, sewage and manure were the primary nitrate sources in major inflow rivers and North Taihu Lake (NTL), while nitrate sources in East Taihu Lake (ETL) probably derived from soil organic N. In summer, atmospheric deposition and sewage/manure inputs appear to play an important role in controlling the distribution of nitrates in the whole lake. The δ(18)O-NO(3)(-) values suggest that the nitrate produced from microbial nitrification is another major nitrate source during both winter and summer months. The variations in isotopic values in nitrate suggest denitrification enriched the heavier isotopes of nitrate in NTL in winter and in ETL in summer.     

Deformities,PCBs, and TCDD-Equivalents in Double-Crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) of the Upper Great Lakes 1986–1991: Testing a Cause-Effect Hypothesis

Deformities have been reported in many species of colonial waterbirds from several localities on the Laurentian Great Lakes. The hypothesis that deformities were caused by either polychlorinated biphenyls (PCBs) or contaminants measured as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs) is tested in this review of available data on concentrations of contaminants in eggs and observed deformities in embryos and chicks of double-crested cormorants (Phalacrocorax auritus) and Caspian terns (Hydroprogne caspia) between 1986 and 1991. Hatched chicks, live and dead eggs retrieved from 37 colonies in the upper Great Lakes were assessed for gross anatomical deformities. Rates of embryo death from seven regions of the upper Great Lakes were measured annually between 1986–1991. Half the embryos found dead in eggs were deformed. Nineteen types of abnormalities or deformities were observed. Subcutaneous edema in cormorants and gastroschisis in terns were the most common abnormalities in live or dead eggs. One of ten crossed-billed cormorant embryos survived to hatch. No bill-deformed terns hatched, although tern embryos had a greater rate of crossed-bills than cormorants. The suite of deformities and abnormalities found was similar to that produced in chickens by exposure to planar polychlorinated biphenyl (pPCB) and dioxin congeners. Hatching and deformity rates were correlated with concentrations ofpPCBs and TCDD-EQs. Planar PCB congeners that contributed most of the TCDD-EQs were present at concentrations sufficient to cause the observed effects. TCDD-EQs measured by H4IIE rat hepatoma cell 7-ethoxyresorufin O-deethylase (EROD) bioassay were highly correlated with deformity rates observed in cormorant chicks, live and dead eggs, and egg death rates. Similar correlations of TCDD-EQs with deformity rates were found in hatched tern chicks, dead eggs, and egg death rates, but not in live eggs. TCDD-EQs were more highly correlated to deformity and embryo death rates than total PCBs. The weight of evidence and these data are sufficient to reject the null hypothesis that there is no causal relationship between the incidence of deformities in cormorants and terns and exposure to planar halogenated compounds measured as TCDD-EQs or total PCBs in the Great Lakes.     

Spatial and seasonal variation in the phytoplankton community of Lake Victoria’s Mwanza Gulf,compared to northern parts of the lake

We investigated the phytoplankton species composition and abundance in two seasons in Mwanza Gulf, Lake Victoria (Tanzania). Phytoplankton was sampled and chlorophyll a content was measured in the dry and wet seasons of 2010–2011 at three stations, from the southern land-inward end of the Gulf towards the open lake. Cyanobacteria, mostly small colonial and filamentous species (e.g., Aphanocapsa spp., Planktolyngbya spp., Merismopedia spp.) dominated at each station (76–95 %), followed by Chlorophyta (5–21 %), whereas the contribution of Bacillariophyceae was small (0–6 %). Phytoplankton densities were generally higher in the rainy season and strongly increased going land-inward from the open lake. Low abundance of N-fixing phytoplankton species suggests that N-fixation was low. The chlorophyll a content in the mouth of the Gulf was low (mean values 4–6 µg/L) compared to values reported previously. Also, chlorophyll a values (means 11–14 µg/L) at land-inward stations of Mwanza Gulf were much lower than those in the northern gulfs (Napoleon Gulf, Murchison Bay and Nyanza Gulf). Between 2002 and 2009 the phytoplankton composition of Mwanza Gulf changed from a community mostly dominated by Bacillariophyceae into a community dominated by Cyanobacteria. In the open water of Lake Victoria, Bacillariophyceae and Cyanobacteria were both abundant. Cyanobacteria dominated both in the three northern gulfs and Mwanza Gulf, but all four showed substantial differences in species and genus compositions. Phytoplankton composition and abundance in Mwanza Gulf differs in many respects from the open water of Lake Victoria and its three northern gulfs.     

How ancient is Lake Lugu (Yunnan,China)? The gastropods’ viewpoint with focus on Radix (Lymnaeidae)

Lake Lugu has been termed an “ancient lake” in several publications. Ancient lakes, such as Baikal or Tanganyika have in common an age of several million years and an outstanding biodiversity and rate of endemism. Lake Lugu’s age is unknown, however, and has been inferred from the presumed Pliocene increased tectonic activity on the Yunnan-Guizhou Plateau. The lake was thus considered to be of tectonic origin, but supporting studies do not exist. Here we report and describe seven endemic species. The endemic gastropod Gyraulus luguhuensis exhibits an aberrant pseudo-dextral shell morphology, which is predominantly known from undisputed ancient lakes. To better understand the origin of the lake and of its biodiversity, we present a preliminary geological study, which shows that Lake Lugu is a tectonic-solution lake. During a survey of the aquatic habitats up to 21 gastropod morphospecies could be differentiated macro-morphologically. An aberrant neritid-like Radix was genetically studied for the first time. The genetic data suggest that Lugu-Radix, typical and neritid shell shapes, constitute a clade, comprising four possibly endemic evolutionary lineages, which potentially represent four different species. The molecular-clock approach indicates a Late Pliocene to Early Pleistocene origin of the clade, which we consider the minimum age of Lake Lugu. Our study reveals that the biodiversity in general and that of gastropods in particular is significantly higher than previously known. Against this background and considering the co-occurrence of aberrant Gyraulus and Radix with an evolutionary history of more than two million years, Lugu is putatively an ancient lake.     

Spatial and temporal variation in sedimentary phosphorus species in Lake Champlain (Vermont,New York,Québec)

We tested the hypothesis that the analysis of operationally defined sedimentary phosphorus species gives a finer resolution of historical land-use changes in lake watersheds than does total phosphorus alone. We measured loosely sorbed/interstitial, reductant soluble, aluminum-bound, apatite, organic and total phosphorus in eleven cores taken from heterogeneous regions of Lake Champlain using sequential extraction. During the pre-settlement period (before 1770 C.E.) concentrations of all P species were low, stable, and dominated by apatite P. With the exception of apatite P, sediment concentrations of all P species increased from pre-settlement times to the present. When accumulation rates were examined, the three P species least susceptible to post-depositional migration (apatite, aluminum-bound, and organic P) were unaffected by deforestation and the development of small, family-scale farms in the 19th century. Increases in accumulation rates were only detected in the early 20th century coincident with afforestation of the watershed as marginal farms were abandoned. By mid-20th century, the accumulation rate of apatite P decreased in all but the lake regions most affected by the industrialization of agriculture and urban development. Aluminum-bound and organic P rates continued to increase in all regions.     

The Evaluation of Kurtboğazı Dam (Ankara,Turkey) from Hydro-Geochemical and Environmental Aspects

Kurtboğazı Dam is one of the most significant sources of drinking water sources for Ankara City. In this study, hydro-geochemical properties and pollution sources of surface waters feeding into the dam are determined. In addition, important environmental problems such as squatter’s houses and wastewater discharges within protection zones of watershed of the dam are defined and appropriate precautions are discussed. The long-term trend (1998–2007) in water quality results of the dam and the surface waters in the Kurtboğazı watershed were studied, utilizing data provided by General Directorate of State Water Works (DSI). The results indicate that waters in the watershed can be classified as waters with calcium-bicarbonate. Due to the drought conditions experienced in recent years, the concentrations of the organic materials and nitrogen and phosphorus compounds in the surface waters have increased dramatically since 2005. It is thought that wastewaters discharged by the settlements within the watershed (especially Pazar Township) are responsible for these increases. Preventing wastewater discharges from the squatter’s houses and agricultural activities on the absolute and the proximate zones of the watershed and the constructing of a sewerage and treatment plant are the first challenges for the protection of the watersheds.     

Monitoring changes of snow cover,lake and vegetation phenology in Nam Co Lake Basin (Tibetan Plateau) using remote SENSING (2000–2009)

The changes of environmental factors such as snow cover, vegetation and hydrologic regime of lakes can reflect ecosystem responses to changing climate. A series of satellite imagery-based environmental data archives including variations in snow cover, vegetation phenology and lake level were mapped in the Nam Co Lake Basin for the period 2000–2009. Results of the synthesis indicate that throughout this period, the average annual snow cover was 19.87% of the total basin, and there is an obvious relation between the elevation and a clear decreasing southeast–northwest trend in snow-cover persistence. Snow mainly happens from October to May. The multi-year mean water storage of Nam Co Lake is 86.40 × 10⁹ m³, with a lake level increase of approximately 2.06 m during the study period. Vegetation phenology showed obvious variation with advanced start of season (SOS) and slightly extended duration of season (DOS). The mean DOS for the Nam Co Lake Basin was 154 days from 2000 to 2009. Affected by air temperature, the SOS dates coincided with snowmelt. The seasonal-variability of climate factors was also studied. The satellite-derived continuous and multiple datasets offer the advantage of monitoring the temporal and spatial trends of each of these metrics and mapping extensive, remote in mountainous areas with no in-situ data such as represented by the Tibetan Plateau.