Issue 3

In this paper the results of a preliminary study that investigates water footprint (WF) concept, as a
useful tool to address water management problems in cultivated areas are presented. The two basic
methodologies reported in the literature, their applicability, benefits and challenges were previously
analyzed and evaluated by Tsoukala et al. (2011). A WF calculation for the crops of Messara valley
in Crete is presented, so as to examine its contribution to achieving effective agricultural policies.
Messara is one of the most important agricultural regions in Greece that faces serious problems in
order to meet crop irrigation demand. The conclusions drawn from this analysis showed that WF can
provide a transparent framework for the identification of potentially optimal alternatives for efficient
water use at river basin catchment level.

Floods are natural disasters that pose a direct threat to human life and often cause significant
economic loss. River floods are caused by heavy and/or prolonged rainfall, causing rivers and
streams to overflow and sometimes also burst dams or levees. Forest fires increase the risk factor to
which humans and properties are exposed during flood events, by intensifying and accelerating the
peak volume of the overflow water. Wildfires alter significantly the geomorphological characteristics
of a river basin, thus affecting both directly and indirectly its hydrological behavior. A forest fire,
followed by a rainfall event, may cause a significant flood downstream. This paper presents a
hydrological analysis of the eastern Attica region, which is performed both prior to and after forest
fire events, in order to assess the change in the consequent flood risk. The study area is the eastern
part of the greater Athens area in Attica (Greece). This is a peri-urban area experiencing rapid urban
growth, and its hydrometeorological conditions are being monitored though a dense hydrometeorological
network for the past 10 years. A fire model is set up to simulate the characteristics of
the development of three hypothetical fire events of low, medium and high severity accordingly. The
parameters that affect fire intensity and rate of spread (e.g. topographic factors such as slope
steepness, elevation, aspect, and configuration of land) are taken into consideration and the
temporal and spatial distribution of a forest fire is studied. Of additional interest in this study is the
fact that a recent forest fire event devastated a significant part of its northern, mountainous area and
the consequences of this event are further examined. A detailed simulation of the three hypothetical
fire scenarios and the real fire event is performed and the outcomes of the analysis are used as an
input in a rainfall – runoff model that allows for an enhanced hydrological study of the affected area.
Land use changes and geomorphological and hydrological alterations as a result of the fire event are
taken into consideration during a post-fire hydrological analysis, which eventually demonstrates the
impact of fire on the hydrological response of the study area. This impact is assessed by means of
application of a methodological framework for the estimation of post-fire values for three hydrological
parameters (CN, initial abstraction and lag time) and the paper concludes that the fire impact has
rendered the downstream areas more prone to floods.

After a prolonged drought period in the early 2000s, the Canadian prairie experienced a remarkably
wet year in 2010. Five stations near the edge of the Saskatchewan boreal forest recorded historically
high cumulative precipitation (from April to September). The exceptional wet year causes the public
concerns on flood controls and land use management in the region. Using the Canadian National
Climate Data Achieve, characteristics of six-month cumulative precipitation sums over
Saskatchewan prairie are investigated by the Generalised Extreme Value (GEV) Theory. Based on
the unconstrained GEV distribution, the 2010 event is outside the estimated 95% confidence
intervals for the five Canadian prairie stations. On the contrary, the exceptional high 2010 cumulative
perception sums for the five stations are still bounded by the estimated confidence bounds if the
GEV distribution is constrained to the Gumbel distribution (i.e. setting the shape factor of the GEV
distribution to be zero). These results demonstrate that the classical extreme analysis is useful for
planning unprecedented extreme events in the Canadian Prairie, if the GEV distribution is
constrained to the Gumbel distribution with the estimated uncertainty bounds based on the order
statistics.

The estimation of evapotranspiration is essential in water resources management. Among a group of
methods, the Penman–Monteith has been commonly applied to calculate reference
evapotranspiration as this method has been also recommended by the Food and Agriculture
Organization of the U.N. (FAO). Other methods widely used are: the FAO 24 Penman, the modified
Blaney and Criddle, the FAO 24 Makkink, and the Hargreaves.
Sensitivity analysis is required to gain a better understanding of the meteorological systems;
particularly to indicate the physical meaning of each meteorological parameter used in the estimation
of the reference evapotranspiration. Several dimensionless sensitivity coefficients have been
proposed, based on the partial derivative of the dependent variable (reference evapotranspiration) to
the independent variables (meteorological variables).
In this paper, a new sensitivity coefficient is proposed to drive sensitivity analysis of the
evapotranspiration methods. The new sensitivity coefficient uses the partial derivative and the
standard deviation of each independent variable. The meteorological variables, whose influence has
been examined, are all the necessary meteorological parameters for the calculation of reference
evapotranspiration, such as temperature, solar radiation, wind speed and relative humidity for each
method. Data from the automatic meteorological station of Aminteo in the Prefecture of Florina,
Western Macedonia, were used. The sensitivity coefficients were calculated for each month, year
and irrigation period. The comparison of the sensitivity coefficients is performed for the month of
water peak demand (July), the irrigation period and the year for each evapotranspiration method.
Results show that the influence of the variables to evapotranspiration is not the same for each
period, and also the order that the variables influence evapotranspiration is changing. A comparison
between the five evapotranspiration methods shows that solar radiation and temperature are the
main parameters that affect evapotranspiration, while relative humidity and wind speed are not so
important for the calculation of evapotranspiration.