Modelling of hydrology and potential population levels at Bronze Age Jawa,Northern Jordan: a Monte Carlo approach to cope with uncertainty

An annual water balance model for Wadi Rajil, in Northern Jordan, is used to simulate the ancient water supply system for the Early Bronze Age site of Jawa. The model includes: water delivery from the catchment; local pond storage; and water demand for people, animals and irrigation. A Monte Carlo approach is used to incorporate the uncertainty associated with a range of factors including rainfall, evaporation, water losses and use. The stochastic simulation provides estimates of potential population levels sustainable by the water supply system. Historical precipitation estimates from a Global Circulation Model, with uncertainty bounds, are used to reconstruct the climate at Jawa in the Early Bronze Age (EBA). Model results indicate that the population levels in the predicted wetter conditions during parts of the EBA could have risen to ∼6000 and may have been higher in wet years. However, palaeoclimatic proxies also suggest prolonged droughts in the EBA; and during these periods the water management system was unable to provide adequate supply for a population of 6000. The utility of Monte Carlo based hydrological modelling as a tool within archaeological science is discussed.     

The Key Role of Water Resources Management in Ecological Restoration in Western China

The interactions of nature and society are intimately reflected in the degradation of the vast, yet diverse, landscapes and ecosystems of arid western China. The development of agriculture, especially irrigation, has altered rivers, soils and ecosystems so much that major ecological rehabilitation and restoration efforts have been needed since 1950. The catchments of the Tarim River in southern Xinjiang (the Tarim Basin) and of the Black River (Hei He) in Gansu Province and western Inner Mongolia provide examples of the benefits, difficulties and conflicts involved in dryland water management. In the early stages of the human development of these catchments, agriculture depending on irrigation using water from these inland rivers was encouraged. The over‐exploitation of these water resources led to such ecological problems as desiccation of lakes, drying out of rivers, degradation of soils and vegetation and lowering of groundwater levels, with consequent environmental and economic impacts. Since 1990 several high‐cost, national projects to re‐establish ecosystems have been initiated. Water is now released from dams in the headwaters of the rivers in order to restore water flows to the dried out lake basins. Such schemes have inevitably led to social problems and difficulties for the people who depended on the water from the dams for local irrigation. The contrasts in adjustments and attitudes over the use of water for agriculture and other economic activities, as opposed to schemes of restoration of ecosystems and ecological engineering, stem largely from two issues; inconsistent provision of information from the scientific community, and differing ideologies, namely environmental protection versus economic development.     

敦煌文献中所见唐五代时期的水利官吏

敦煌文献中保存了许多唐五代时期地方各级水利官吏的设置运作状况记录。唐代前期设都水令,为当时敦煌“统以千渠”的最高级别水利官员。中唐吐蕃统治时期设“水官”“部落水官”以及“水监”“部落水监”“地方总水监”。晚唐五代归义军时期专设水司,长官为都渠泊使,下设多名水官。敦煌绿洲四界及寿昌灌区分别设置多名有特殊责任的水官“平水”,以“平治水利”,平水“相量”为务。此外,每条灌渠、每座斗门均设渠头或斗门长,属基层一级。这套水利官吏系统层层负责,相互配合,有效保证了农田灌溉顺利进行。同时敦煌民间还自发地组织起一批“渠人社”,这对地方政府水利管理体系是有益的补充。研究历史上水利官吏系统及其运作状况,对今天河湖运行和治理管护也具有借鉴作用。     

Assessing Regional Crop Irrigation Requirements and Streamflow Availability for Irrigation Development in Saginaw Bay,Michigan

Spatial and temporal variability of soil, crop, and climate significantly affects the estimates of regional irrigation requirements. This paper incorporates soil association data and multiple-station, multiple-year climate data into four simulation models, CERES-MAIZE, SOYGRO, BEANGRO, and YIELD to account for the spatial and temporal variability of the input parameters in estimating the evapotranspiration rates and irrigation requirements of corn, drybean, soybean, and sugarbeet production in the Saginaw Bay basin, Michigan. The Thiessen method was used to delineate the spatial coverage of the weather stations in the study watershed. The results of the simulated crop irrigation requirements at the soil association level were multiplied by the weights of each soil association area to derive regional irrigation requirements. The availability of streamflow at different exceedence probabilities was evaluated to determine the maximum irrigation area the stream is able to sustain without causing water quality degradation. Through a case study of the Saginaw Bay irrigation development, this paper demonstrates that the spatial and temporal variability of soil, crop, and climate can be well represented in the simulation models to provide more realistic simulation results in support of irrigation decision making.     

Assessing Regional Crop Irrigation Requirements and Streamflow Availability for Irrigation Development in Saginaw Bay,Michigan

Spatial and temporal variability of soil, crop, and climate significantly affects the estimates of regional irrigation requirements. This paper incorporates soil association data and multiple-station, multiple-year climate data into four simulation models, CERES-MAIZE, SOYGRO, BEANGRO, and YIELD to account for the spatial and temporal variability of the input parameters in estimating the evapotranspiration rates and irrigation requirements of corn, drybean, soybean, and sugarbeet production in the Saginaw Bay basin, Michigan. The Thiessen method was used to delineate the spatial coverage of the weather stations in the study watershed. The results of the simulated crop irrigation requirements at the soil association level were multiplied by the weights of each soil association area to derive regional irrigation requirements. The availability of streamflow at different exceedence probabilities was evaluated to determine the maximum irrigation area the stream is able to sustain without causing water quality degradation. Through a case study of the Saginaw Bay irrigation development, this paper demonstrates that the spatial and temporal variability of soil, crop, and climate can be well represented in the simulation models to provide more realistic simulation results in support of irrigation decision making.     

LOCATIONAL SIGNALING AND AGGLOMERATION

Agglomeration can be caused by asymmetric information and a locational signaling effect: The location choice of workers signals their productivity to potential employers. The cost of a signal is the cost of housing at that location. When workers' marginal willingness to pay for housing is negatively correlated with their productivity, only the core‐periphery (partially stratified) equilibria are stable. When workers' marginal willingness to pay for housing and their productivity are positively correlated, there is no core‐periphery equilibrium. The urban wage premium is explained when there is a core‐periphery equilibrium. Furthermore, location can at best be an approximate rather than a precise sieve for high‐skill workers.     

Irrigator relations with water in the Sunraysia region,northwestern Victoria

Irrigated agriculture faces significant challenges under climate change, and may not be feasible in parts of the Murray‐Darling Basin beyond 2050. Recent research into the cultural politics of water has paid limited attention to the water cultures and relations of irrigators in Minority World countries. We analyse the water relations of grape farm irrigators in the Sunraysia region of Victoria using interviews and farm tours undertaken between 2014 and 2016. Findings are summarised under five themes: (1) the sociality of irrigation water, (2) temporal and spatial relations, (3) the risk of rain, (4) the micro‐scale of water knowledge, and (5) environment as actor. These themes shed light on the diverse relations that constitute both environmental and irrigation water. Irrigators are embedded in these relations at multiple scales, local and distant, mediated by technology and infrastructure. The scale of our focus makes visible water and other forms of environmental knowledge that often go unnoticed in broader debates over irrigation. The concept of “the environment”, understood as an embodied actor in policy discourse and by irrigators, is an emergent trend that warrants ongoing research attention.     

Duopoly prices under congested access*

Abstract. Consider two firms, at different locations, supplying a homogenous good at constant marginal production cost. Consumers incur travel costs to the firm for each unit purchased, and the travel costs increase with the amount of travel to each firm (congestion). When all traffic and all congestion are generated by travel to a duopolist, both the Nash–Bertrand equilibrium prices and the Nash–Cournot equilibrium prices exceed the sum of the marginal production cost and the marginal external travel cost. However, when the road is shared by travelers to the duopolists' facilities and travelers in competitive markets, the Nash–Bertrand duopoly price equals the competitive price and the Nash–Cournot price contains a markup.     

Water,Rules and Gender: Water Rights in an Indigenous Irrigation System,Marakwet, Kenya

The management of indigenous irrigation systems has received increasing attention both from social science researchers and from those development agents who seek to change them, or to find in them a model for organizing newly developed irrigation schemes. This article discusses how water is allocated within one such irrigation system, the hill furrow irrigation of the Marakwet escarpment in Kenya. It describes the ‘formal rules’ of water rights, giving particular attention to the issue of gender with respect to water rights. It then discusses the ‘working rules’ relevant to water allocation, involving various informal practices of sharing, buying and stealing. The implications of this complexity for understanding the operation of indigenous farmer-managed irrigation systems are examined.     

Basic Problems of the Transformation of Nature in Central Asia

A review of broad research problems leading to ultimate transformation of the Central Asian environment for the purpose of expanding irrigated agriculture and desert grazing. The problems are: land resources and reclamation needs for irrigation purposes; the water and salt regime of irrigated fields, regional types and methods of control; the water and salt budget of irrigated areas and means of determining and regulating it; the hydrologic cycle of Central Asia and ways of transforming it for irrigation purposes; and the use of forage and water resources for expanding the desert grazing economy.     

Geographic Information Systems (GIS) hydrological modeling in archaeology: an example from the origins of irrigation in Southwest Arabia (Yemen)

From small bands of foragers, pastoralists, and village agriculturists, to states and civilizations water accessibility and management played a crucial role in sustenance and social life throughout the ancient world. Recent advances in Geographic Information Systems (GIS) and related remote sensing technologies offer powerful means of analyzing water flow that are well-suited to clarify design and operational requirements of different irrigation and water management systems. Ancient Southwest Arabian irrigation technologies developed over thousands of years culminating in some the ancient world's most advanced flashflood water systems. This paper describes satellite imagery Digital Elevation Model (DEM) extraction and GIS hydrological modeling procedures conducted for the Wadi Sana watershed of Hadramawt Governate, Yemen. Results help illustrate one of the local contexts in which small-scale irrigation originated in Southwest Arabia and additionally serve as an example for those interested in applying similar methods in other regions.     

Temporal Patterns and Effects of Surface‐Water Diversions on Daily Flows and Aquatic Habitats: Bega‐Bemboka River,New South Wales,Australia

An understanding of the nature and magnitude of hydrological, physical habitat and physico‐chemical effects resulting from surface‐water diversions in river systems is essential for effective management of water resources. For most coastal‐draining rivers in New South Wales, however, there are few data available on irrigation diversions, their hydrological impacts and environmental effects. This paper therefore presents an analysis of mean daily surface‐water diversions for pasture irrigation from approximately three years of metered data and the resultant effects on daily flows and aquatic habitats in the Bega‐Bemboka River. The period of analysis of the hydrological effects of irrigation diversions is extended to the full length of record (approximately five years) for gauging stations most affected by irrigation diversions, using Maintenance of Variance Extension Type 1 (MOVE.1) modelling techniques. The annual mean, median and peak daily rates of water diversion by metered surface‐water licences used to irrigate 925 ha of dairy pasture are 10.5 Ml d^?1, 7.3 Ml d^?1 and 41.5 Ml d^?1, respectively. Diversion effects on flow duration statistics are such that the measured 90th and 95th daily flow duration percentiles at the gauging station most affected by upstream irrigation diversions are equivalent to the 97th and 99th flow duration percentiles, respectively, under MOVE.1 modelled natural flow conditions. While diversions for irrigation over the three‐year data period account for only 6.6% of total flow volumes, diversions as a proportion of daily surface‐water inflows increase exponentially under decreasing flow rates. Median and maximum daily diversion rates attain 91% and 118%, respectively, of total surface‐water inflows to the diversion‐affected reach when upstream inflows range from 15 to 20 Ml d^?1. This exponentially‐increasing relationship between daily diversion rates and declining surface‐water inflows suggests that ‘rule of thumb’ guidelines on sustainable diversion limits based on mean or median annual percentage diversion volumes need to be applied cautiously to river systems with no or limited capacity to manipulate flows to meet downstream consumptive demands.     

Can Dasymetric Mapping Significantly Improve Population Data Reallocation in a Dense Urban Area?

The issue of reallocating population figures from a set of geographical units onto another set of units has received a great deal of attention in the literature. Every other day, a new algorithm is proposed, claiming that it outperforms competitor procedures. Unfortunately, when the new (usually more complex) methods are applied to a new data set, the improvements attained are sometimes just marginal. The relationship cost‐effectiveness of the solutions is case‐dependent. The majority of studies have focused on large areas with heterogeneous population density distributions. The general conclusion is that as a rule more sophisticated methods are worth the effort. It could be argued, however, that when we work with a variable that varies gradually in relatively homogeneous small units, simple areal weighting methods could be sufficient and that ancillary variables would produce marginal improvements. For the case of reallocating census data, our study shows that, even under the above conditions, the most sophisticated approaches clearly yield the better results. After testing fourteen methods in Barcelona (Spain), the best results are attained using as ancillary variable the total dwelling area in each residential building. Our study shows the 3‐D methods as generating the better outcomes followed by multiclass 2‐D procedures, binary 2‐D approaches and areal weighting and 1‐D algorithms. The point‐based interpolation procedures are by far the ones producing the worst estimates.     

城镇可持续生活供水价格研究--以陕西省关中地区为例

本分析了关中地区城镇生活水价现状和问题,得出了城镇生活水价是不可持续的结论,即水价低于供水生产成本,水价结构不合理。在探讨可持续水价的调整原则的基础上,提出了价格杠杆调节关中生活水价的措施,包括：逐步把水价调整到成本水价以上的水平,并调整水价结构,使之能反映供水成本和水资源价值;实行累进加价制度,对超定额用水征收高水价;实施季节性水价等。     

Hydrology of the combination irrigation system in the Wadi Faynan, Jordan

The field system of the Wadi Faynan in southern Jordan was fed by an ancient combination irrigation system that incorporated runoff farming and diversion irrigation techniques. The hydraulic characteristics of this system were most probably designed to take advantage of the confluence of three tributary streams. A theoretical model of discharge produced by runoff is based on contemporary ground conditions and historic climate reconstructions. The design principles of the main hydraulic features are examined and velocity and discharge measurements in principal conveyance irrigation channels are reconstructed. The design of this hydraulic system took into account the environmental constraints and opportunities of the area and maximized different sources of water in the catchment using various techniques of water collection.     

Incorporating Soil Associations into Linear Programming Models for Development of Irrigation Scenarios

An inadequate streamflow supply in Saginaw Bay, Michigan, affects the irrigation development in the region. Linear programming (LP) models are developed in this paper to help irrigation planners determine optimal irrigation scenarios. To incorporate the spatial variations of the soil and climate into the optimization models, soil associations are used as the basic analysis unit for estimating crop yields, irrigation requirements, and expected economic returns. The yields and irrigation requirements of corn, drybeans, and soybeans are simulated by the CERES-MAIZE, BEANGRO, and SOYGRO models at each of the twelve soil associations in the study area over the period of 1951–1980. The yield and irrigation requirement of sugarbeets are simulated by the YIELD model for all the soils in the study area over the period of 1956–1987. The crop prices, simulated crop yields and irrigation requirements, and variable costs are used to compute the expected gross margins and other coefficients in the LP models. The optimization results provide irrigation scenarios that are linked to specific soil associations, which are more useful to decision makers for identifying and targeting individual soils for irrigation development than are the spatially lumped optimal solutions. This study demonstrates that through integration of GIS and simulation models, spatial variations of the climate, soil, and water resources can be better represented in the optimization models to produce more realistic irrigation scenarios.     

Estimating the Marginal Willingness to Pay for Commuting

With informational frictions on the labor market, hedonic wage regressions provide biased estimates of the willingness to pay for job attributes. We show that a recent theoretical result, which states that the variation in job durations provides a basis for obtaining good estimates, can be generalized to a wide class of search models. We apply this result by estimating the marginal willingness of employed workers to pay for commuting, using Dutch longitudinal data. The average willingness to pay for one hour commuting is estimated to equal almost half of the hourly wage rate.     

Mode Choice,Commuting Cost,and Urban Household Behavior*

Abstract. In this paper, we extend the partial equilibrium urban model of DeSalvo (1985) to include mode choice. DeSalvo demonstrated that the urban model of Muth (1969) was robust to the extension to leisure choice. We show that the model is robust to mode choice as well. In addition, we derive the comparative static results that commuters choose higher speed modes for longer commutes, at higher wage rates, with greater tastes for housing, and with lower housing prices. Also, for a given distance commuted, we derive the comparative static result that commuters chose shorter duration commutes at higher wage rates. Whereas it is typically assumed that marginal commuting cost is positive and non‐increasing with distance, we derive these results. Moreover, we derive the results that marginal commuting cost rises with an exogenous increase in housing price and falls with increased tastes for housing. We also explore the effects of exogenous commuting‐cost changes on the endogenous variables of the model. The remaining comparative static results on housing consumption and location are qualitatively the same as in DeSalvo.     

Historical Perspectives on Pre-Colonial Irrigation in Southern Africa

Abstract

One of the basic areas of interaction between water as natural resource and human societies as agents of cultural transformation is the technology of irrigation. In Africa at least 66 per cent of the available water is used for purposes of irrigation. For more than 4 000 years irrigation has secured food supplies for humans on a continent that is noted for its relative shortage of sufficient natural water supplies.

There is a remarkable hidden power of water in the history of southern Africa. This is particularly the case when we consider the development of early irrigation technologies of Iron Age farmers. The small irrigation furrow of the subsistence farmer was just as important to an insular community of Bantu-speaking people in pre-colonial times, as is the sophisticated irrigation technology in present-day South Africa. Currently there is a paucity of information about pre-colonial indigenous irrigation technology. This can be ascribed to a number of factors of which the invasion of modern Western traditions in the nineteenth century is perhaps the most important. A number of other factors for the apparent blind-spot is also presented in this study.

In southern Africa there are traces of indigenous pre-colonial irrigation works at sites such as Nyanga in Zimbabwe; the Limpopo River Valley; Mpumalanga; and South Africa's eastern Highveld. Reference is also made in this article to specific strategies of irrigation used by Iron Age communities, prior to the advent of a colonial presence. Finally, attention is also drawn to pre-colonial land tenure and state formation against the backdrop of Wittfogel's theories on hydraulic society.     

The Long-Term Transformation of Nature and Changes in the Atmospheric Moisture Supply of the European Part of the USSR

The author estimates the magnitude of changes in the precipitation and moisture-and-heat regime of the European part of the USSR that may result from additional evaporation related to irrigation and other reclamation measures in the arid south. He finds that such measures may result in a southward shift of the boundaries of natural zones by about 100 kilometers.