27 research outputs found
Using hydrologic landscape classification and climatic time series to assess hydrologic vulnerability of the western U.S. to climate
We apply the hydrologic landscape (HL) concept to assess the hydrologic vulnerability of the western United States (U.S.) to
projected climate conditions. Our goal is to understand the potential
impacts of hydrologic vulnerability for stakeholder-defined interests across
large geographic areas. The basic assumption of the HL approach is that
catchments that share similar physical and climatic characteristics are
expected to have similar hydrologic characteristics. We use the hydrologic landscape vulnerability approach (HLVA) to map the HLVA index (an assessment
of climate vulnerability) by integrating hydrologic landscapes into a
retrospective analysis of historical data to assess variability in future
climate projections and hydrology, which includes temperature,
precipitation, potential evapotranspiration, snow accumulation, climatic
moisture, surplus water, and seasonality of water surplus. Projections that
are beyond 2 standard deviations of the historical decadal average contribute to the HLVA index for each metric. Separating vulnerability into
these seven separate metrics allows stakeholders and/or water resource
managers to have a more specific understanding of the potential impacts of
future conditions. We also apply this approach to examine case studies. The
case studies (Mt. Hood, Willamette Valley, and Napa–Sonoma Valley) are important to the ski and wine industries and illustrate how our approach
might be used by specific stakeholders. The resulting vulnerability maps
show that temperature and potential evapotranspiration are consistently
projected to have high vulnerability indices for the western U.S.
Precipitation vulnerability is not as spatially uniform as temperature. The
highest-elevation areas with snow are projected to experience significant changes in snow accumulation. The seasonality vulnerability map shows that
specific mountainous areas in the west are most prone to changes in seasonality, whereas many transitional terrains are moderately susceptible.
This paper illustrates how HL and the HLVA can help assess climatic and
hydrologic vulnerability across large spatial scales. By combining the HL
concept and HLVA, resource managers could consider future climate conditions
in their decisions about managing important economic and conservation
resources.</p
Catchment classification:hydrological analysis of catchment behavior through process-based modeling along a climate gradient
Catchment classification is an efficient method to synthesize our understanding of how climate variability and catchment characteristics interact to define hydrological response. One way to accomplish catchment classification is to empirically relate climate and catchment characteristics to hydrologic behavior and to quantify the skill of predicting hydrologic response based on the combination of climate and catchment characteristics. Here we present results using an alternative approach that uses our current level of hydrological understanding, expressed in the form of a process-based model, to interrogate how climate and catchment characteristics interact to produce observed hydrologic response. The model uses topographic, geomorphologic, soil and vegetation information at the catchment scale and conditions parameter values using readily available data on precipitation, temperature and streamflow. It is applicable to a wide range of catchments in different climate settings. We have developed a step-by-step procedure to analyze the observed hydrologic response and to assign parameter values related to specific components of the model. We applied this procedure to 12 catchments across a climate gradient east of the Rocky Mountains, USA. We show that the model is capable of reproducing the observed hydrologic behavior measured through hydrologic signatures chosen at different temporal scales. Next, we analyze the dominant time scales of catchment response and their dimensionless ratios with respect to climate and observable landscape features in an attempt to explain hydrologic partitioning. We find that only a limited number of model parameters can be related to observable landscape features. However, several climate-model time scales, and the associated dimensionless numbers, show scaling relationships with respect to the investigated hydrological signatures (runoff coefficient, baseflow index, and slope of the flow duration curve). Moreover, some dimensionless numbers vary systematically across the climate gradient, possibly as a result of systematic co-variation of climate, vegetation and soil related time scales. If such co-variation can be shown to be robust across many catchments along different climate gradients, it opens perspective for model parameterization in ungauged catchments as well as prediction of hydrologic response in a rapidly changing environment
Uncertainty in hydrological signatures for gauged and ungauged catchments
Reliable information about hydrological behavior is needed for water‐resource management and scientific investigations. Hydrological signatures quantify catchment behavior as index values, and can be predicted for ungauged catchments using a regionalization procedure. The prediction reliability is affected by data uncertainties for the gauged catchments used in prediction and by uncertainties in the regionalization procedure. We quantified signature uncertainty stemming from discharge data uncertainty for 43 UK catchments and propagated these uncertainties in signature regionalization, while accounting for regionalization uncertainty with a weighted‐pooling‐group approach. Discharge uncertainty was estimated using Monte Carlo sampling of multiple feasible rating curves. For each sampled rating curve, a discharge time series was calculated and used in deriving the gauged signature uncertainty distribution. We found that the gauged uncertainty varied with signature type, local measurement conditions and catchment behavior, with the highest uncertainties (median relative uncertainty ±30–40% across all catchments) for signatures measuring high‐ and low‐flow magnitude and dynamics. Our regionalization method allowed assessing the role and relative magnitudes of the gauged and regionalized uncertainty sources in shaping the signature uncertainty distributions predicted for catchments treated as ungauged. We found that (1) if the gauged uncertainties were neglected there was a clear risk of overconditioning the regionalization inference, e.g., by attributing catchment differences resulting from gauged uncertainty to differences in catchment behavior, and (2) uncertainty in the regionalization results was lower for signatures measuring flow distribution (e.g., mean flow) than flow dynamics (e.g., autocorrelation), and for average flows (and then high flows) compared to low flows.Key Points:We quantify impact of data uncertainty on signatures and their regionalizationMedian signature uncertainty ±10–40%, and highly variable across catchmentsNeglecting gauging uncertainty causes overconditioning of regionalizationPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137249/1/wrcr21917-sup-0001-2015WR017635-s01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137249/2/wrcr21917.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137249/3/wrcr21917_am.pd
Diagnosis and treatment of thyroid cancer in children in the multicenter analysis in Poland for PPGGL
Introduction: Differentiated thyroid carcinoma (DTC) in
children presents different biological behavior in comparison
to adults. Authors presents preliminary results of multicenter
analysis concerning incidence, diagnostics and treatment
of DTC in children.
Material and methods: The study is a retrospective analysis
of 107 pediatric patients from 14 academic centers based
on the data from 2000 to 2005 obtained by questionnaire in
hospitals involved in the treatment of DTC in children.
Results: Papillary thyroid cancer was diagnosed in 83 children,
follicular thyroid cancer in 10 children and medullary
thyroid cancer in 14 children. Incidence of DTC in children
was estimated between 18 and 23 cases per year. The biggest
group of patients consisted of children between 11 and
15 years of age, with girls to boys ratio 3.3 : 1. Clinically DTC
in children presented most often as solitary thyroid nodule.
Cervical lymphadenopathy was observed in 42% of patients.
Intraoperative verification indicated metastatic nodes
in 50% of children. Low stage DTC predominated (T1
in 36% and T2 in 26% of children). One step surgery was performed in 65% of children with DTC, two step surgery
in 25% of patients. I131 therapy was undertaken in 80% of
children. Lung metastases were indicated in post therapeutic
studies in 14% of children with DTC. Prophylactic thyroidectomies
were performed in 79% of children in the group
of patients with MTC and RET gene mutations.
Conclusions: The necessity of introduction of unified therapeutic
standard in children with DTC in Poland is underlined.Wstęp: Zróżnicowane raki tarczycy (DTC, differentiated thyroid
carcinoma) występują u dzieci rzadko. Większość przypadków
wykrywanych jest w wieku 11-17 lat. W odróżnieniu
od dorosłych DTC u dzieci prezentują odmienne zachowanie
biologiczne. Mała liczba przypadków DTC
w poszczególnych ośrodkach oraz względnie łagodny ich
przebieg utrudniają ocenę występowania i leczenia DTC
u dzieci w Polsce, uzależniając ją od wysiłków włożonych
w uzyskanie rzetelnych danych. Autorzy przedstawiają
wstępne wyniki analizy wieloośrodkowej dotyczące występowania,
diagnostyki i leczenia DTC u dzieci.
Materiał i metody: Podjęte badania są retrospektywną analizą
obejmującą lata 2000-2005, opartą na danych z historii
chorób uzyskanych z ankiet rozesłanych do ośrodków dla
dzieci i dorosłych podejmujących leczenie DTC. Do analizy
zgłoszono 107 pacjentów z 14 ośrodków akademickich
w Polsce. Analizie poddano wiek i płeć dzieci z DTC, wielkość
i lokalizację zmian w tarczycy, sposoby rozpoznawania
DTC, rodzaje i zakres wykonywanych zabiegów operacyjnych
oraz leczenie uzupełniające izotopem J131.
Wyniki: Raka brodawkowatego stwierdzono u 83 dzieci,
pęcherzykowego u 10 dzieci, a rdzeniastego u 14 dzieci. Częstość
występowania DTC u dzieci w Polsce wahała się między
18 a 23 przypadkami rocznie. W województwach: mazowieckim
i połączonych wielkopolskim i lubuskim wykazano
w okresie 2000-2005 wyższą (24 i 25) częstość występowania
DTC, w pozostałych województwach wykazywano
od 2 do 10 przypadków DTC. Największą grupę pacjentów
stanowiły dzieci w wieku 11-15 lat, a stosunek dziewcząt do chłopców wynosił 3,3 : 1. Klinicznie DTC prezentowały
się najczęściej jako pojedyncze guzki tarczycy. Limfadenopatię
szyjną w badaniu klinicznym stwierdzono
u 42% pacjentów, a śródoperacyjnie u 50% dzieci. U większości
pacjentów dominowały niższe stopnie zaawansowania
DTC (T1 u 36% i T2 u 26% dzieci). Operacje jednoetapowe
wykonano u 65% dzieci, operacje dwuetapowe u 25%
dzieci, a profilaktyczne tyreoidektomie u 79% dzieci z grupy
pacjentów z rakiem rdzeniastym tarczycy (MTC, medullary
thyroid cancinoma) i mutacją genu Ret. Leczenie izotopowe
J131 podjęto u 80% dzieci. Przerzuty do płuc w scyntygrafii
poterapeutycznej wykazano u 14% dzieci z DTC.
Wnioski: We wnioskach podkreśla się konieczność wdrożenia
na terenie całego kraju ujednoliconego i ocenianego
na podstawie obiektywnych przesłanek sposobu postępowania
z dziećmi z DTC
Climate-vegetation-soil interactions and long-term hydrologic partitioning: signatures of catchment co-evolution
Budyko (1974) postulated that long-term catchment water balance is controlled to first order by the available water and energy. This leads to the interesting question of how do landscape characteristics (soils, geology, vegetation) and climate properties (precipitation, potential evaporation, number of wet and dry days) interact at the catchment scale to produce such a simple and predictable outcome of hydrological partitioning? Here we use a physically-based hydrologic model separately parameterized in 12 US catchments across a climate gradient to decouple the impact of climate and landscape properties to gain insight into the role of climate-vegetation-soil interactions in long-term hydrologic partitioning. The 12 catchment models (with different paramterizations) are subjected to the 12 different climate forcings, resulting in 144 10 yr model simulations. The results are analyzed per catchment (one catchment model subjected to 12 climates) and per climate (one climate filtered by 12 different model parameterization), and compared to water balance predictions based on Budyko's hypothesis (<i>E/P</i> = ϕ (<i>E</i><sub>p</sub>/<i>P</i>); <i>E</i>: evaporation, <i>P</i>: precipitation, <i>E</i><sub>p</sub>: potential evaporation). We find significant anti-correlation between average deviations of the evaporation index (<i>E</i>/<i>P</i>) computed per catchment vs. per climate, compared to that predicted by Budyko. Catchments that on average produce more <i>E</i>/<i>P</i> have developed in climates that on average produce less <i>E</i>/<i>P</i>, when compared to Budyko's prediction. Water and energy seasonality could not explain these observations, confirming previous results reported by Potter et al. (2005). Next, we analyze which model (i.e., landscape filter) characteristics explain the catchment's tendency to produce more or less <i>E</i>/<i>P</i>. We find that the time scale that controls subsurface storage release explains the observed trend. This time scale combines several geomorphologic and hydraulic soil properties. Catchments with relatively longer subsurface storage release time scales produce significantly more <i>E</i>/<i>P</i>. Vegetation in these catchments have longer access to this additional groundwater source and thus are less prone to water stress. Further analysis reveals that climates that give rise to more (less) <i>E</i>/<i>P</i> are associated with catchments that have vegetation with less (more) efficient water use parameters. In particular, the climates with tendency to produce more <i>E</i>/<i>P</i> have catchments that have lower % root fraction and less light use efficiency. Our results suggest that their exists strong interactions between climate, vegetation and soil properties that lead to specific hydrologic partitioning at the catchment scale. This co-evolution of catchment vegetation and soils with climate needs to be further explored to improve our capabilities to predict hydrologic partitioning in ungauged basins
Technical Note: Characterizing hydrologic change through catchment classification
There has been an intensive search in recent years for suitable strategies to organize and
classify the very heterogeneous group of catchments that characterize our
landscape. One strand of this work has focused on testing
the value of hydrological signatures derived from widely available
hydro-meteorological observations for this catchment classification effort.
Here we extend this effort by organizing 314 catchments across the
contiguous US into 12 distinct clusters using six signature
characteristics for a baseline decade (1948–1958, period 1). We subsequently
develop a regression tree and utilize it to classify these catchments for
three subsequent decades (periods 2–4). This analysis allows us to assess
the movement of catchments between clusters over time, and therefore to assess
whether their hydrologic similarity/dissimilarity changes. We find examples
in which catchments initially assigned to a single class diverge into
multiple classes (e.g., midwestern catchments between periods 1 and 2), but also
cases where catchments from different classes would converge into a single
class (e.g., midwestern catchments between periods 2 and 3). We attempt to
interpret the observed changes for causes of this temporal variability in
hydrologic behavior. Generally, the changes in both directions were most
strongly controlled by changes in the water balance of catchments
characterized by an aridity index close to one. Changes to climate
characteristics of catchments – mean annual precipitation, length of cold
season or the seasonality of precipitation throughout the year – seem to
explain most of the observed class transitions between slightly
water-limited and slightly energy-limited states. Inadequate temporal
information on other time-varying aspects, such as land use change, limits
our ability to further disentangle causes for change
Characterizing hydrologic change through catchment classification
There has been an intensive search in recent years for suitable strategies to organize and
classify the very heterogeneous group of catchments that characterize our
landscape. One strand of this work has focused on testing
the value of hydrological signatures derived from widely available
hydro-meteorological observations for this catchment classification effort.
Here we extend this effort by organizing 314 catchments across the
contiguous US into 12 distinct clusters using six signature
characteristics for a baseline decade (1948–1958, period 1). We subsequently
develop a regression tree and utilize it to classify these catchments for
three subsequent decades (periods 2–4). This analysis allows us to assess
the movement of catchments between clusters over time, and therefore to assess
whether their hydrologic similarity/dissimilarity changes. We find examples
in which catchments initially assigned to a single class diverge into
multiple classes (e.g., midwestern catchments between periods 1 and 2), but also
cases where catchments from different classes would converge into a single
class (e.g., midwestern catchments between periods 2 and 3). We attempt to
interpret the observed changes for causes of this temporal variability in
hydrologic behavior. Generally, the changes in both directions were most
strongly controlled by changes in the water balance of catchments
characterized by an aridity index close to one. Changes to climate
characteristics of catchments – mean annual precipitation, length of cold
season or the seasonality of precipitation throughout the year – seem to
explain most of the observed class transitions between slightly
water-limited and slightly energy-limited states. Inadequate temporal
information on other time-varying aspects, such as land use change, limits
our ability to further disentangle causes for change
Catchment classification: Empirical analysis of hydrologic similarity based on catchment function in the eastern USA
Hydrologic similarity between catchments, derived from similarity in how catchments respond to precipitation input, is the basis for catchment classification, for transferability of information, for generalization of our hydrologic understanding and also for understanding the potential impacts of environmental change. An important question in this context is, how far can widely available hydrologic information (precipitation-temperature-streamflow data and generally available physical descriptors) be used to create a first order grouping of hydrologically similar catchments? We utilize a heterogeneous dataset of 280 catchments located in the Eastern US to understand hydrologic similarity in a 6-dimensional signature space across a region with strong environmental gradients. Signatures are defined as hydrologic response characteristics that provide insight into the hydrologic function of catchments. A Bayesian clustering scheme is used to separate the catchments into 9 homogeneous classes, which enable us to interpret hydrologic similarity with respect to similarity in climatic and landscape attributes across this region. We finally derive several hypotheses regarding controls on individual signatures from the analysis performed here.Civil Engineering and Geoscience