Disaggregation modelling of monthly streamflows using a new approach of the method of fragments

Abstract

The method of fragments is applied to the generation of synthetic monthly streamflow series using streamflow data from 34 gauging stations in mainland Portugal. A generation model based on the random sampling of the log-Pearson Type III distribution was applied to each sample to generate 1200 synthetic series of annual streamflow with an equal length to that of the sample. The synthetic annual streamflow series were then disaggregated into monthly streamflows using the method of fragments, by three approaches that differed in terms of the establishment of classes and the selection of fragments. The results of the application of such approaches were compared in terms of the capacity of the method to preserve the main monthly statistical parameters of the historical samples.

Editor D. Koutsoyiannis; Associate editor C. Onof

Citation Silva, A.T. and Portela, M.M., 2012. Disaggregation modelling of monthly streamflows using a new approach of the method of fragments. Hydrological Sciences Journal, 57 (5), 942–955.     

B) Organisations internationales

Abstract

A modification of Svanidze's fragments method was applied to generate synthetic samples of monthly inflows to the La Angostura and Malpaso dams, located on the Grijalva River, in the state of Chiapas, Mexico. This modification allows generation of the monthly runoff of several dams in a series and preservation of their cross-correlations. Comparing statistics of generated and historical series, a good agreement between them was observed, especially for the autocorrelations between consecutive months and for cross-correlations between both dams, except for slight differences in the standard deviation and the skewness during the dry period.     

Genetic improvement of New Zealand aquaculture species: programmes,progress and prospects

Aquaculture, like terrestrial farming, cannot achieve economic and sustainable production without high performing genetic stocks tailored to the conditions under which they are grown. It is essential, therefore, that aquaculture investment includes genetics and biotechnology to adapt marine livestock to the novel conditions of intensive aquaculture and to the demanding markets into which they are sold. The return on investment in well-structured breeding programmes can be very high, and significant performance and economic gains have been demonstrated in multiple species. Many factors must be considered in designing a genetic improvement programme, including the reproductive biology of the species and the identification of realistic and commercially relevant breeding goals based on the resources and facilities available. This paper reviews the options available to aquaculturists and provides examples of how these are being applied to six aquaculture species in New Zealand: king salmon, hāpuku, kingfish, Greenshell^TM mussels, Pacific oysters and pāua (abalone).     

Breeding habitat selection by houbara bustard (Chlamydotis[undulata] macqueenii) in Mori, Xinjiang, China

The breeding habitat selection by houbara bustards in Mori, Xinjiang, China duringthe breeding seasons from April to June 1998-2000 was studied. Most of habitats chosen forbreeding were short sub-shrubby and open areas close to high bushy patches. The nesting re-males clearly prefer Iow covered areas and avoid densely covered and high vegetation sites. Thenumber of herb species was significantly smaller at nest sites than at randomly selected sites.Only the distance to the closest fox den contributed the most to discrimination between successfuland predated nests. The average distance to the closest fox den was significantly longer at suc-cessful nests than at depredated nests. Vegetative density, plant species richness, topography anddistance to the closest fox den are possibly the most important factors that determined the nestsites selection of houbara bustard. The displaying males clearly prefer Iow covered areas andavoid densely covered and high vegetation sites. The vegetation density and number of plant spe-cies at display sites was significantly lower than that at randomly selected sites. The average dis-tance to the closest bushy patch was significantly shorter at display sites than at random sites.Plant species richness, vegetative density, vegetative cover and distance to the bushy patches arepossibly the most important factors for the display sites selection of houbara bustard.     

Desertification and animal biodiversity in the desert grasslands of North America

Studies of breeding birds and small mammals were conducted at a series of sites that form a gradient of severity of desertification. Desert grassland sites represented the least changed landscape units and mesquite coppice dunes represented the most severe degradation, an irreversibly degraded landscape unit. The hypothesis that desertification reduces species diversity was not supported by the data. Species richness and diversities (Shannon-Weaver H′) of breeding birds were higher in the desertified areas than in the grassland with one exception. Data from a site dominated by the exotic African grass,Eragrostis lehmanniana, in south-eastern Arizona showed that breeding bird diversity was lower at that site than at a site in the same region that was dominated by native grasses. Species richness, diversity (H′), and abundance of small mammals were also higher in desertified areas than in desert grassland. Most grassland species of birds and mammals persist in the desertified habitats and species that are characteristic of shrublands colonize desertified desert grasslands. This accounts for the increases in species richness. However some species such as the banner-tailed kangaroo rat,Dipodomys spectabilis, are eliminated when grassland degrades to mesquite coppice dune or eroded creosotebush communities. These data suggest that other measures of faunal biodiversity such askeystone speciesmay be better measures of the impact of desertification on animal biodiversity.     

Effects of seasonal breeding on productive performance of pastoral goat herds in northern Kenya: a longitudinal analysis of growth in kids and body weight development of does

This paper investigates whether liveweight development of kids and dams can be improved by introducing a seasonal breeding regime in goat herds maintained under pastoral management in northern Kenya. The experimental treatment consisted of six consecutive mating seasons. Traits studied comprise relative growth rates of kids (g kg^−0·75 day⁻¹) from birth until 2 years of age, liveweight development of kids (kg) from birth until 2 years of age, and body weight development (kg) of does over a reproductive cycle of 1 year duration. No systematic effect of mating season on birth weights of kids could be detected, whereas the experiment succeeded in demonstrating that mating season has an impact upon body weight development of kids. The highest average preweaning weight gains were achieved by kids born in the period from October to May, while growth performance was seriously compromised when birth took place at the middle of the long dry season. However, the differences between mating season groups had almost completely disappeared by 1 year of age. The mating season treatment produced marked differences in weight development curves in does. During gestation, does were advantaged when they were mated just prior to the long rainy season, while the largest relative liveweight gains over the entire reproductive cycle were achieved by does mated during the short rains. It is concluded that seasonal breeding does not confer any major advantage in terms of liveweight production of young livestock, except that mating during the short dry season from December to January should be avoided. Similarly, a clear effect on body weights of does at the end of the reproductive cycle could only be observed when mating occurred during this period.     

BREEDING A BETTER CHINA: PIGS,PRACTICES, AND PLACE IN A CHINESE COUNTY, 1929–1937*

ABSTRACT. From 1929 to 1937, Chinese reformers in the Mass Education Movement attempted to transform pigs and pig breeding in Dingxian, Hebei, through the importation of an American breed of pig and its hybridization with local pigs. This episode provides a case study for the investigation of the roles played in scientific work by local Chinese materials and practices on one hand and Western scientific principles and methods on the other. Reformers were conscious that the wholesale importation and implementation of Western science had failed China in the past and suspected that it would fail again. Their chief concern was that the new pig should raise production levels but still “suit local conditions.” But “conditions” and “methods” do not play equal roles in science, and reformers did not require the scientific methods of pig breeding to negotiate with local methods. Despite their attention to local conditions, the reformers thus assumed that modern, Western science was universal in nature and that it could and should be applied universally, replacing local knowledge and practices.     

高产赤霉素菌株选育

针对赤霉素工业生产菌株皆为多核多细胞菌丝型,不产生孢子的特性,首先将赤霉素菌丝体通过酶解手段,溶去其细胞壁使其成为单一细胞游离的原生质体,并在此基础上通过紫外线等理化诱变,使其产生基因突变,然后在再生平板上,使赤霉素原生质体中的突变型菌株得到再生,最后通过摇瓶筛选,得到一株生产水平高、生产性能稳定的高产赤霉素菌株。     

Potential Effects of Global Warming on Waterfowl Populations Breeding in the Northern Great Plains

The Prairie Pothole Region (PPR) of the Northern Great Plains is the most important breeding area for waterfowl in North America. Historically, the size of breeding duck populations in the PPR has been highly correlated with spring wetland conditions. We show that one indicator of climate conditions, the Palmer Drought Severity Index (PDSI), is strongly correlated with annual counts (from 1955 to 1996) of both May ponds (R2 = 0.72, p < 0.0001) and breeding duck populations (R2 = 0.69, p < 0.0001) in the Northcentral U.S., suggesting the utility of PDSI as an index for climatic factors important to wetlands and ducks. We then use this relationship to project future pond and duck numbers based on PDSI values generated from sensitivity analyses and two general circulation model (GCM) scenarios. We investigate the sensitivity of PDSI to fixed changes in temperature of 0°C, +1.5°C, +2.5°C, and +4.0°C in combination with fixed changes in precipitation of -10%, +0%, +7%, and +15%, changes spanning the range of typically-projected values for this region from human-induced climatic change. Most (11 of 12) increased temperature scenarios tested result in increased drought (due to greater evapotranspiration under warmer temperatures) and declining numbers of both wetlands and ducks. Assuming a doubling of CO2 by 2060, both the equilibrium and transient GCM scenarios we use suggest a major increase in drought conditions. Under these scenarios, Northcentral U.S. breeding duck populations would fluctuate around means of 2.1 or 2.7 million ducks based on the two GCMs, respectively, instead of the present long-term mean of 5.0 million. May pond numbers would fluctuate around means of 0.6 or 0.8 million ponds instead of the present mean of 1.3 million. The results suggest that the ecologically and economically important PPR could be significantly damaged by climate changes typically projected. We make several recommendations for policy and research to help mitigate potential effects.     

日本刺沙蚕Neanthes japonica (Iznka)大规模育苗的初步研究

结合生产实践 ,模拟野外温度、盐度等环境条件 ,在较大规模的育苗池环境条件下 ,对日本刺沙蚕胚胎和发育作了生殖生物学的观察和描述 ,为人工增养殖日本刺沙蚕提供了基础资料