Linking MODFLOW with an Agent-Based Land-Use Model to Support Decision Making

The U.S. Geological Survey numerical groundwater flow model, MODFLOW, was integrated with an agent-based land-use model to yield a simulator for environmental planning studies. Ultimately, this integrated simulator will be used as a means to organize information, illustrate potential system responses, and facilitate communication within a participatory modeling framework. Initial results show the potential system response to different zoning policy scenarios in terms of the spatial patterns of development, which is referred to as urban form, and consequent impacts on groundwater levels. These results illustrate how the integrated simulator is capable of representing the complexity of the system. From a groundwater modeling perspective, the most important aspect of the integration is that the simulator generates stresses on the groundwater system within the simulation in contrast to the traditional approach that requires the user to specify the stresses through time.     

Influence of oscillating flow on hyporheic zone development

The hyporheic zone is an ecologically important ecotone that describes the extent to which nutrient-rich surface waters penetrate the shallow subsurface adjacent to a flowing surface water body. Although steady-state models satisfactorily explain the incursion of surface water into the subsurface as a function of head gradients developed across streambed riffles, they fail to account for the depth that surface water is observed to penetrate the subsurface or for the extent to which the hyporheic zone develops adjacent to the stream channel. To investigate these issues, transient flow modeling has been conducted at the riffle scale and supported by data for an instrumented site in northern Ontario where stream-stage fluctuations are strictly regulated. Model results show that daily stream-stage fluctuations between 0.6 and 4 m produce oscillating solute flow paths that typically reduce residence times of water and solutes in the hyporheic zone from 60 days or more under steady-state conditions to less than 1 day. Furthermore, similar stream-stage fluctuations increase the depth that solutes pervade the subsurface and banks lateral to the stream from around 1 m under steady-state conditions to as much as 2 and 10 m, respectively. The results demonstrate that the transient flow conditions triggered in the subsurface by variable stream stage can exert a strong influence on hyporheic zone development and have important implications for the hyporheos. The results are especially important for hyporheic communities that may survive gradual changes to their living conditions by migrating to more hospitable aquatic habitats, but are unable to respond to rapid changes provoked by more extreme hydrological events.     

Adaptation and poverty reduction in Mozambique: an opportunity for developing countries to lead§

Climate change disproportionately impacts the world’s poorest countries. A recent World Bank report highlighted that over 100 million people are at risk of falling into extreme poverty as a result of climate change. There is currently a lack of information about how to simultaneously address climate change and poverty. Climate change challenges provide an opportunity for those impacted most to come up with new and innovative technologies and solutions. This article uses an example from Mozambique where local and international partners are working side-by-side, to show how developing countries can simultaneously address climate change and poverty reduction using an ecosystem-based adaptation approach. Using ecosystem-based adaptation, a technique that uses the natural environment to help societies adapt to climate change, developing countries can lead the way to improve climate adaptation globally. This paradigm shift would help developing countries become leaders in ecosystem-based adaptation and green infrastructure techniques and has implications for climate policy worldwide.

POLICY RELEVANCE

The Paris Agreement resulting from the United Nations Framework Convention on Climate Change (UNFCCC) 21st Conference of Parties (COP 21) in December 2015 was rightly lauded for its global commitment to cut greenhouse gas emissions. However, COP 21 was also historic because of its call for non-party stakeholders to address climate change, inclusion of a global goal of ‘enhancing adaptive capacity, strengthening resilience and reducing vulnerability’, and the United States’ commitment of $800 million to adaptation funding. The combination of recognizing the need for new stakeholders to commit to climate change adaptation, the large impact climate change will have on the developing world, and providing access to funds for climate change adaptation creates a unique opportunity for developing countries to pave the way in adaptation policies in practices. Currently, developing countries are creating National Adaptation Plans (NAPs) for the UNFCCC. Through including a strong component of ecosystem-based adaptation in NAPs, developing countries can shape their countries’ policies, improve local institutions and governments, and facilitate a new generation of innovative leaders. Lessons learned in places like Mozambique can help lead the way in other regions facing similar climatic risks.     

Propagation of coastal‐trapped waves under an ice cover in Hudson Bay*

Abstract

Three arrays of current‐meter moorings were deployed under landfast sea ice in southeast Hudson Bay for eight weeks in spring 1986. Spectral analysis shows low‐frequency signals with periods of 3 to 11 days. These signals are interpreted as being due to coastal‐trapped waves propagating cyclonically in Hudson Bay; their theoretical dispersion relations and corresponding modal structures are presented for winter stratification and are compared with observations. At a period of 3 days both the modified external Kelvin wave and higher mode continental shelf waves may be important in describing the observed low‐frequency variability, whereas at a period of 10 days the Kelvin wave appears to be the dominant mode. The generation mechanisms for these coastal trapped waves are also investigated. Two sources have been studied: the longshore atmospheric pressure gradient and the average atmospheric pressure over the ice cover in Hudson Bay. Coherence and phase analyses performed with time series of longshore current and atmospheric forcing data reveal that both the average atmospheric pressure and the longshore atmospheric pressure gradient are important in explaining the observed low‐frequency variability, without indicating which one is the most important.     

Role of hypsometry and planform in basin hydrologic response

The effects of variations of drainage basin morphometry and relief characteristics on flood peak magnitude and time-to-peak are investigated using simulated stream networks. The networks are produced by three models: headward growth, systematic capture, and minimum power relaxation. Translational and kinematic wave flood routing were used to generate synthetic hydrographs. Peak discharge and time-to-peak are predictable to a high degree by five different sets of morphometric-relief parameters. In order of decreasing order of importance in predictive ability the parameters characterize basin size, relative relief, basin concavity, and basin shape. Both simulated and natural stream networks exhibit strong dependence of planimetric morphometry upon basin concavity. The effect of this dependency is to increase the effect of basin concavity upon flood hydrographs.     

A large-scale pattern in the solar magnetic field

A clearly evident large-scale pattern in the interplanetary magnetic field during 1964 is used to search for a similar large-scale pattern in the solar magnetic field. It is found that such a pattern did exist in the photospheric field observations on both sides of the equator over a range of at least 40°N to 35°S. The pattern is basically similar at all these latitudes, and differs from that to be expected from solar differential rotation in three important respects. It is found that the solar magnetic pattern changed at all latitudes investigated within an interval of a few solar rotations.     

Remote spectroscopic identification of carbonaceous chondrite mineralogies: Applications to Ceres and Pallas

High-resolution spectroscopic observations of asteroids Ceres and Pallas have been obtained in the 1.0- to 2.6-μm region. Combined with previous spectralmeasurements at other wavelengths, this work presents the broadband spectral reflectances of these asteroids over the 0.4 to 3.6-um region. This extended coverage permits new analyses of the surface mineralogies of these objects. Using laboratory comparison spectra of meteorites and mixtures of terrestrial minerals, the surfaces of Ceres and Pallas are consistent with mixtures of opaques and hydrated silicates, such as are found in types C1 and C2 meteorites. This research emphasizes the importance of the 3-um spectral region for studying by remote methods the relationship of carbonaceous chondrite mineralogies to asteroid surfaces.     

Polar magnetic fields of the Sun: 1960–1971

Observations of the magnetic fields in the polar regions of the Sun are presented for the period 1960–1971. At the start of this interval the fields at the two poles were consistently of opposite sign and averaged around 1 G. Early in 1961 the field in the south decreased suddenly and the field in the north decreased in strength slowly over the next few years. By the mid-1960's the fields at both poles were quite weak and irregular. Throughout the period of these observations the fields at both poles often showed a remarkable tendency to vary in unison. About the middle of 1971 the north polar field became significantly positive, first at lower latitudes, then above 70 °. An autocorrelation analysis of the polar fields in the north shows a weak rotation peak, indicating significant features in these regions. A comparison of field strengths in the east and west quadrants in the north suggests that even at the extreme polar latitudes the following polarity fields are inclined slightly toward the rotation and the preceding polarity field lines are inclined slightly to trail the rotation.