An outstanding question for snowmelt-dominated watersheds of the western US is the response of stream flow to changes in climate. We know little about mountain aquifers because they commonly involve structurally complicated rocks, extreme head gradients (ground slope angles 10-40°), and dramatically fluctuating recharge due to seasonal snow-melt. In general, the western United States is predicted to face warmer temperatures and more frequent and prolonged droughts, and we can expect to see a decrease in annual snowpack, earlier onset of snowmelt, and increased evaporation.

A field training school has been organized in Nantes (France) in August 2008 about urban water hydrology. Twenty researchers (seniors and graduate students) attended this summer school intended to learn more about the quantification of pollution fluxes in urban water systems. The aim is now to extend this first experience and to organize an international field training school during the summer 2010.

 Seventy-four catchments, with a total area of 790 km2 (ranging from 1 to 50 km2), drain from the Santa Ynez Mountains along the northern coast of Santa Barbara Channel. The topography of these coastal catchments is characterized as mountainous headwaters and sloping coastal plains separated by transitional foothills. From west to east, there are both elevational and land use gradients. Headwater elevations increase from approximately 300 to 1400 m, and land uses on the coastal plain and foothills change from mostly rangeland to a combination of urban and agricultural lands.

Elevational Controls on Organic and Inorganic Nutrients in Stream Waters, Boulder Creek Watershed, Colorado Front Range

Jordan N. Parman and Mark W. Williams

Department of Geography and Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA

Understanding the impacts of landuse and/or climate change on streamflow characteristics, such as peak discharge, sediment transport capacity, flow velocities and depths, within a given region or watershed requires knowledge of fine scale (0.01-10 m) hydraulic channel properties (i.e., detailed cross-sections, roughness, bed material). However, data for channel/reach properties are limited to primarily in-situ measurements.

Reach scale experiments have shown that transient storage (TS) zones may be important controls on nitrogen (N) export to coastal waters. We investigated the relative impact that main channel (MC), surface TS (STS) and hyporheic TS (HTS) have on N removal at the network scale using an N removal model applied to the Ipswich River in Massachusetts, USA.

Surface/groundwater water interactions are defined as the exchange of water across the soil/sediment water interface. In the Everglades National Park (ENP), these interactions may be important not only for the transport of water, but also for the transport of nutrients and chemicals. The Everglades ecosystem is drained by two major water ways: Shark and Taylor Slough. Sloughs are depressions with slightly deeper water than in the adjacent marshes. Taylor Slough is located in the southeastern corner of ENP and regulates Florida Bay fresh water inflows.

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial melt water streams. We propose that the dynamics of meltwater generation and sub-stream thaw depth control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Little is known about the temporal variability of nutrient fluxes to the Dry Valley lakes.

It is well established that hydrological and ecological processes are closely coupled in natural ecosystems. The nature of this coupling is greatly altered in urban environments, where the built environment has modified ecosystem structure and function. These alterations are particularly pronounced in arid urban environments where the hydrological response is typically very flashy. We present a conceptual model of ecohydrological interactions in arid urban environments, focusing on feedbacks among hydrology, ecosystem structure, biogeochemistry, and erosion across multiple spatial scales.

The prospect for long term, interdisciplinary research continues to grow since the "regionalizing" of the Coweeta and North Temperate Lakes LTER sites and the initiation of the two urban LTER sites: Baltimore and Central-Arizona-Phoenix. Additional sites have recruited social scientists and expanded both the questions asked and the geographic extent of their interests. Thus, there is growing opportunities for collaboration among sites that might not identify themselves as "urban," in conjunction with the existing regional and urban sites.