University of California Water Resources Center

The Lisbon metropolitan region has grown rapidly in population since 1970, due largely to the immigration of people from former Portuguese colonies in Africa and from rural areas of the country in pursuit of higher living standards. Much of this population growth was accommodated clustered high-rise apartment blocks (many unpermitted) in the region west of Lisbon, in the municipalities Oeiras, Cascais, Sintra, and Amadora. These developments were largely unplanned, often did not provide for sewage treatment, and lack adequate mass transit or urban amenities such as parks and other open spaces. Moreover, because the main transport axes run east-west, it is difficult for residents of these apartment blocks to go the relatively short distance southward to the coast (e.g., only 10 km from Cacém to the coast).

This region is drained by a set of subparallel streams (each draining about 20-50 km2), flowing roughly north-south through deeply incised valleys to debouch into the Atlantic between Lisbon and Cascais. With rapid urbanization peak runoff has increased, resulting from larger impervious surfaces and sewage from illegal housing settlements. Many reaches have been canalized within concrete walls to increase flood capacity, eliminating physical habitat complexity, and reducing amenity and recreational values. However, the urbanization has occurred mostly on uplands, leaving the bottomlands of the incised stream valleys in many reaches surprisingly unaltered. For decades, these drainages were largely neglected, managed mostly to convey floodwaters, although in some reaches there was strong informal use of the stream corridor and floodplains (such as garden plots). The Water Framework Directive (WFD) adopted by the EU Parliament (2000), has motivated extension and improvement of the regional sewer network to improve water quality. The WFD requires that all water bodies in member states achieve ‘Good Ecological Status’ by 2015, defined in terms of hydromorphological, biological, and physico-chemical quality elements of stream reaches, based on characteristics documented at reference sites.

Located 15 km west of Lisbon, Ribeira da Barcarena-Jardas drains a 35 km2 catchment, whose uppermost reaches are forested, but otherwise alternates between urbanization and remnant agricultural and open-space uses. With improved sewage treatment and water quality, there is strong potential to preserve and restore ecological functions, consistent with goals of ‘good ecological status.’ As illustrated by the successful urban stream project in Cacém, there is tremendous potential for the stream corridor to provide parkland for the dense urban settlements. Through GIS analysis of remotely-sensed data, and field surveys of water quality, habitat structure, riparian vegetation, and fish populations, an interdisciplinary workshop of graduate students from Berkeley and Lisbon analyzed potential opportunities to enhance ecological values and human access along the stream. Our analysis indicated that implementation of stormwater management strategies via relatively unobtrusive retrofits of small open bits of urban land and floodplain within the catchment could mitigate many of the negative hydrologic effects of urbanization. By virtue of its linear nature, the stream corridors could provide pedestrian and bicycle connections from population centers (now under-served by parklands) to cultural features and to coastal beaches and trails. A trail could inspire similar efforts on neighboring, parallel basins that have undergone similar urbanization pressures and face similar challenges in providing underserved urban populations with access to recreation and contact with nature.

In Mediterranean climates, mild year-round temperatures support comfortable human settlement with rich agricultural regions. The climate’s long summer drought, seasonal river flow, high inter-annual variability in precipitation, and episodic floods threaten these settlements, leading to highly manipulated hydrologic systems.

The degree of hydrological alteration and consequent ecological change is typically much greater in Mediterranean-climate rivers than humid-climate systems. Dams, diversions, irrigation channels, storage and distribution facilities simultaneously restrict flow regimes, support economic development and destroy the native biological communities in Mediterranean drainage basins. Overcoming the complex relationships among climate, economy and our entangled legal and political institutions challenge the restoration potential of Mediterranean-climate river systems worldwide.

Throughout the world there is increasing public awareness of the importance of sustainable water management to meet both growing human demands and ecosystem needs. Predictions of increased climate variability and indicators of ecological and water quality deterioration have made water management a salient political issue, particularly in arid climate regions such as western North America and the Iberian Peninsula. In recent years, substantial effort has been focused on adopting sustainable water use practices and mitigating the impacts to natural rivers and streams resulting from human activities. Yet the restoration of natural biological communities has been more difficult than anticipated. Our inability to effectively restore and protect rivers and groundwater sources are in part due to the scale of environmental damage inflicted upon them, but also are a consequence of the legal and institutional frameworks under which water is managed. Assessments of the current state of the world’s water resources suggest that conventional approaches to water management will be inadequate to sustainably balance human and ecosystem needs into the future. Furthermore, as nations around the world struggle with water management challenges, there has been little explicit attempt for one region to learn from the experience of another in approaching common problems.

The European Union’s Water Framework Directive (WFD) defines a new strategy for meeting human water demands while protecting environmental functions and values and may be helpful in informing water management practices and policies in other regions of the world. In the report we explore how the management approach described under the WFD compares to the legal and institutional system of a California river basin, managed under distinctly different principles and objectives. Through a theoretical application of the WFD, we highlight the critical water management challenges of northern California’s Russian River basin and use the Directive’s approach to develop strategic recommendations for water management reform.

Land subsidence caused by the excessive use of groundwater resources has traditionally caused serious and costly damage to the Los Banos-Kettleman City area of California's San Joaquin Valley. Although the arrival of surface water from the Central Valley Project has reduced subsidence in recent decades, the growing instability of surface water supplies has refocused attention on the future of land subsidence in the region. This report develops a three-dimenslonal, numerical simulation model for both groundwater flow and land subsidence. The simulation model is calibrated using observed data from 1972 to 1998. A probable future drought scenario is used to consider the effect on land subsidence of three management alternatives over the next thirty years. Maintaining present practices virtually eliminates unrecoverable land subsidence, but with a growing urban population to the south and concern over the ecological implications of water exportation from the north, it does not appear that the delivery of surface water can be sustained at current levels. The two other proposed management alternatives reduce the dependency on surface water by increasing groundwater withdrawl. Land subsidence is confined to tolerable levels in the more moderate of these proposals, while the more aggressive produces significant long-term subsidence. Finally, an optimization model is formulated to determine maximum groundwater withdrawl from nine water sub-basins without causing irrecoverable subsidence over the forecasted period. The optimization reveals that withdrawl of groundwater supplies can be increased in certain areas in the eastern side of the study area without causing significant subsidence.

Seepage from rivers and natural channels is a serious problem in the Sacramento Valley of California. Impairment of land use occurs along the Sacramento, Feather, Yuba and Bear Rivers as a result of intermittent periods of high ground water or ponded surface water. When channel levels exceed the adjacent ground surface elevation, water moves through and under the confining levels into adjacent lands. If drainage facilities are inadequate, the soil becomes saturated and water often ponds on the surface. The water damages orchards and perennial and annual crops, and prevents working of land, resulting in delays in or prevention of normal planting of annual crops.