Economic Analysis of Alternative Flood Control Measures by Digital Computer

The purpose of this project was to develop a digital computer program for selecting the optimum combination of flood proofing, flood-plain land use, channel improvement, and residual flood damage for a given floodplain. Based on economic efficiency, the optimum policy is selected for each planning unit of the total flood-plain for each period of time called a planning stage. The program was written in Fortran IV for the IBM 7040 and the University of Kentucky Computing Center compiler. The program requires about 23,000 words of core storage and about 30 seconds of execution time per planning-unit-stage for typical conditions. The program is not intended to furnish a finished design but is intended to select the optimum combination of flood control measures and residual flooding with regard to both time and space. The program was used to test the sensitivity of the optimum combination of measures to variation in discount rate, right-of-way value, population projections, value of open space amenities, adversion to large annual variation in flood damage, costs of restricting flood-plain land use, costs of flood proofing, and costs of channel improvements. It was also used to analyze the effectiveness of land use, flood proofing, and channel improvement used individually and in various combinations. Program development and sensitivity studies were based on data previously collected for the Morrison Creek Watershed near Sacramento, California

Economic Analysis of Alternative Flood Control Measures

Within the last few years, the growing realization that an effective flood control program must include non-structural measures (land use management and flood proofing) has resulted in Presidential Executive Order 11296 requiring Federal agencies to seek the optimum combination of structural and non-structural measures for flood control. The requirement has created a dilemma. No methodology is available for systematic evaluation of alternative combinations of structural and non-structural measures. Prospective procedures are too time consuming to be feasible under current financial and manpower limitations. The only way out is to perform much of the planning process by digital computer. With this goal, two flood control planning programs have been developed. Each program systematically selects the optimum combination of channel improvement, flood proofing, and land use management by location within the flood plain and by time. The second program adds detention storage to the list of available alternatives. Both programs contain the entire planning process by going all the way from raw data to a selected optimum program of measure use in one run. However, the programs are not intended to produce a finished design. Their use should be followed by a final field check to verify the input data and preparation of the plans and specifications necessary for implementation. The programs have been applied to a series of flood hazard areas in California and Kentucky and indicated an optimum flood control program in a small fraction of the time spent in current planning methods. They free the planning engineer from spending most of his time in routine calculations and allow more time for consideration of qualitative and intangible factors

First Observation of the Submillimeter Polarization Spectrum in a Translucent Molecular Cloud

Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM, but a troublesome contaminant for studies of cosmic microwave background polarization. In each case, an understanding of the significance of the polarization signal requires well-calibrated physical models of dust grains. Despite decades of progress in theory and observation, polarized dust models remain largely underconstrained. During its 2012 flight, the balloon-borne telescope BLASTPol obtained simultaneous broadband polarimetric maps of a translucent molecular cloud at 250, 350, and 500 μm. Combining these data with polarimetry from the Planck 850 μm band, we have produced a submillimeter polarization spectrum, the first for a cloud of this type. We find the polarization degree to be largely constant across the four bands. This result introduces a new observable with the potential to place strong empirical constraints on ISM dust polarization models in a previously inaccessible density regime. Compared to models by Draine & Fraisse, our result disfavors two of their models for which all polarization arises due only to aligned silicate grains. By creating simple models for polarized emission in a translucent cloud, we verify that extinction within the cloud should have only a small effect on the polarization spectrum shape, compared to the diffuse ISM. Thus, we expect the measured polarization spectrum to be a valid check on diffuse ISM dust models. The general flatness of the observed polarization spectrum suggests a challenge to models where temperature and alignment degree are strongly correlated across major dust components