F. Water Resources
RAP's water resource-related activities were considerable in FY04. Research expanded into flash flood nowcasting as part of an NCAR Opportunity Fund study and new work in climate change research methods for water resource assessment was partially supported by NCARs Climate and Weather Impact Assessment Science Initiative (CWIASI). RAPs land surface modeling work was advanced through the addition of a new 2-D overland flow routing parameterizations to the NOAH Land Surface model, the land surface model used by the Weather Research Forecasting (WRF) mesoscale model and the Mesoscale Model Version 5 (MM5). RAP also played a major role in the North American Monsoon Experiments (NAME) Intensive Observing Period (IOP) in Summer 2004 by the deployment and analysis of a comprehensive rain gage network, and establishing an operational mesoscale forecasting model applied during the IOP.
Denvers Urban Drainage and Flood Control District (UDFCD) manages the ALERT (Automated Local Evaluation in Real Time) urban flood warning system, whose aim is to reduce injuries, deaths, and property damage caused by floods. Floods in urban and semi-urban environments are the leading cause of weather-related accidental death in the U.S. The goal of this 2004 Opportunity Fund project was to demonstrate the usefulness of NCARs Thunderstorm Identification Tracking and Analysis (TITAN) data in support of the UDFCD flood threat monitoring and dissemination mission.
Figure F-1 is a flow diagram showing how radar data are combined to produce watershed-specific estimates and 30- min forecasts of rainfall accumulation over specific, GIS-specified UDFCD watersheds. These data are transformed into XML format, placed on an ftp server for broadcast, and then picked up by web-based and Microsoft Excel© tools operated by the UDFCD for visualization of storm movement and basin discharge estimates and forecasts.
Figure F-1. Data flow diagram of basin precipitation estimates and forecast products.
Two outputsare produced by the UDFCD based on the XML data distributed in real time on an NCAR ftp server as depicted in Figure F-1. These include estimates and forecasts of basin runoff of Boulder Creek (Figure F-2a) and a radar image display that shows TITAN storm tracks and precipitation threshold of the Lena Gulch Watershed for 9 June 2004 (Figure F-2b). [Top]
Figure F-2 a) UDFCD basin runoff estimates (blue-line) and forecasts (red-line) for the Boulder Creek watershed, based on the XML distributed file shown in Figure F1; b) UDFCD Scalable Vector Graphics (SVG) display of background radar reflectivity, current TITAN storm locations given as ellipses (ellipse color depicts reflectivity intensity, with scale not shown).
In addition to this work, Hatim Sharif, David Yates, Rita Robers, and Cindy Mueller applied RAPs Auto-Nowcast (ANC) system to flood forecasting. ANC combines a host of remotely sensed data, including gridded radar fields, surface mesonet data, sounding data, satellite data, etc. to produce 0-60 min quantitative precipitation nowcasts through deterministic and fuzzy logic algorithms. The potential benefits of ANC precipitation nowcasts were demonstrated by forcing them through a physically-based, distributed hydrologic model to predict flash floods in a small, highly urbanized catchment in Denver, CO. Two rainfall events on 5 and 8 July 2001 in the Harvard Gulch watershed corresponding to times during which the ANC system operated (Figure F-3) were analyzed. In addition to analyzing the nowcasts for these events, the 8 July case was used to evaluate the hydrologic models ability to accurately reproduce the watersheds response to the precipitation forcing based on either rain-gage or high-resolution radar estimates.
Figure F-3. The Harvard Gulch watershed, with storm-total radar estimated rainfall, and location of USGS rain gauges are depicted. The street network of the urban area are shown in the background.
The final report noted the slightly higher annual average rainfall in the northern part of the Oman Mountains, while a second maximum was located further to the southeast, in more mountainous terrain. The seasonal distribution of rainfall helps explain these differences, as the northern precipitation maximum is more strongly influenced by winter- time precipitation. In the winter and early spring, cold frontal troughs originate in the North Atlantic and Mediterranean Sea and move south across the United Arab Emirates toward the Oman mountains. Summer rainfall maxima (bottom panel of Figure F-4), exhibit the suspected strong relationship between rainfall and topography. The rainfall footprint of the southern Al Hajar al Gharbi mountain range is larger than that of the north, since the orographic influence dominates. Given the frequency of convection over the Oman Mountains in the summer, it was concluded that storms over Oman should be amenable to seeding with hygroscopic flares and that acquisition of a modern weather radar is necessary to begin longer-term evaluation.
1) for winds between 6-8 ms-1
, modulation of the surface energy budget by vegetation effects, or
During Summer 2004, the multinational, multi-institutional, North American Monsoon Experiment (NAME) executed its principal field campaign, or Enhanced Observation Period (EOP). Numerous instrument platforms including weather radars, atmospheric sounding systems, wind profilers, rain gauges, aircraft and ocean vessels were deployed to the 'Tier I' region (See Figure F-5; box bounded by dotted line) of southwestern North America. These instruments monitored surface and atmospheric conditions during the summer rainy season in July and August. David Gochis serves as a member of the NAME Science Working Group, which directs NAME research activities and also serves as a Principal Investigator in the NAME program. Under this role D. Gochis built a Geographical Information System (GIS) database to aid in the planning and implementation of the EOP instrument network. With colleagues at the University of Arizona and in Mexico, D. Gochis has been working on diagnosing and modeling key aspects of the rainfall climatology in western Mexico and its relationship to regional streamflow. This work has culminated in the production two recent manuscripts describing the topographic dependency of diurnal rainfall characteristics in western Mexico, and the intra-seasonal evolution of streamflow in response to monsoon rains.
Figure F-5. 2004 NAME EOP Instrument Network.
The collaboration between NCARs Research Applications Program and the Environment and Societal Impacts Group with the AWWA (American Water Works Association) Research Foundation advanced in FY04, with a workshop held on 16 March 2004. The workshop brought together water utility planners and climate scientists to discuss the scientific basis of climate change to address how water utilities might plan appropriately for the effect of global warming on water resources. The workshop also facilitated communication between specialists in climactic change and professionals in water utilities to guide future research directions.
This project completed a useful and timely primer to help water managers incorporate climate change information into their planning process. The workshop highlighted the difficulty in incorporating climate change into water management decisions, mainly due to the layers of uncertainty inherent in assessing climate change impacts. For example, uncertainty in projected greenhouse gas emissions, limitations of climate models, and loss of accuracy when climate forecasts are downscaled to watershed resolution and imperfections in hydrological models, are all relevant.
A review of the scientific and water planning literature suggests that most water resource and water utility studies have incorporated climate change information into their planning process using a top-down approach. This approach typically begins by establishing the scientific credibility of climate change, develops future climate scenarios that can be used at the regional level, and then imposes those potential changes on water resource systems for assessing, for example, system reliability. The problem with a top-down approach is that it is not always driven by the unique needs of a utility and also the approach is rooted in the uncertainty of the future climate projections, those projections differing substantially from model-to-model and from region-to-region. Thus, the results are often disregarded for lack of relevancy and reliability.
The primer to be submitted to the AWWA Research Foundation in late 2004 will suggest alternatives to this approach, including a bottom-up strategy which begins by identifying a water utility's most critical vulnerabilities; articulates the causes for those vulnerabilities; suggests how climate change, climate variability, and climate extremes might exacerbate those vulnerabilities; and finally designs an analytic process to better address and solve the vulnerability in the face of the climatic uncertainty (e.g. a no-regret approach). At the heart of either top-down or bottom-up approaches is Integrated Water Resource Management (IWRMM), which is regarded as the most effective approach for assessing and changing the regulatory environment with its competing demands, whose methods will be further articulated in the primer.
A new project began between the Department of Water Resource Studies (DWRS) in Abu Dhabi, United Arab Emirates (UAE), and NCAR, where RAP (Roelof Bruintjes and Tara Jensen) is implementing a customized hydro-meteorological analysis and display system for the DWRS. The main components of this system include a numerical weather prediction and analysis module based on MM5, running on a 48-node Linux cluster system; a geospatial database containing historical and real-time observations from meteorological and hydrological platforms, and model analysis fields; a tool to perform complex queries to the database; a display system giving the user an integrated view of the geospatial database holdings with flexible controls that include layering GIS information from commercial GIS tools; and providing connectivity of the geospatial database to third-party GIS vendor tools, such as ESRIs ArcView or ArcInfo.
The last ten months have seen the initial deployment of the system. Figure F-7 shows a beta version of a hydrometeorology display (uaeViz) giving Real Time Four Dimensional Data Assimilation (RTFDDA)/MM5 forecasts of air temperature (colored grid) and contoured relative humidity. In addition, the system is now capable of creating custom reports based on the selection of meteorological stations and meteorological fields from which to derive climatological statistics (Figure F-8).
Figure F-7. UAE-Visualization of RT-FDDA forecast output over the United Arab Emirates, the Arabian Gulf and the Gulf of Oman.