Spatial water table level modelling with multi-sensor unmanned aerial vehicle data in boreal aapa mires

Peatlands have been degrading globally, which is increasing pressure on restoration measures and monitoring. New monitoring methods are needed because traditional methods are time-consuming, typically lack a spatial aspect, and are sometimes even impossible to execute in practice. Remote sensing has been implemented to monitor hydrological patterns and restoration impacts, but there is a lack of studies that combine multi-sensor ultra-high-resolution data to assess the spatial patterns of hydrology in peatlands. We combine optical, thermal, and topographic unmanned aerial vehicle data to spatially model the water table level (WTL) in unditched open peatlands in northern Finland suffering from adjacent drainage. We predict the WTL with a linear regression model with a moderate fit and accuracy (R2 = 0.69, RMSE = 3.85 cm) and construct maps to assess the spatial success of restoration. We demonstrate that thermal-optical trapezoid-based wetness models and optical bands are strongly correlated with the WTL, but topography-based wetness indices do not. We suggest that the developed method could be used for quantitative restoration assessment, but before-after restoration imagery is required to verify our findings

HAKUSANOJEN OPTIMOINTI MOBIILISOVELLUKSEN MARKKINOINNISSA GOOGLE PLAY STORESSA

Opinnäytetyö tutkii hakusanojen optimointia Google Playn sovelluskaupassa. Tarkoituksena on kehittää osaamista, jolla mobiilisovelluskehittäjät saisivat sovelluksensa markkinointiin lisää tehoa aiheesta, josta löytyy niukalti aikaisempaa suomenkielistä tutkimusmateriaalia. Hakuoptimointi on osa mobiilisovelluskaupan optimoinnin toimenpiteitä (englannin kielen sanoista application store optimization tai ASO). ASO puolestaan kuuluu mobiilisovelluksen markkinoinnin toimenpiteisiin. Työn tavoitteena on kehittää hakuoptimoinnin menetelmien osaamista. Teoreettinen viitekehys pohjautuu alan ammattilaisten tekemiin e-kirjoihin, artikkeleihin ja oppaisiin. Myös kirjalähteitä on, jotka käsittelevät erityisesti kuluttajakäyttäytymistä ja tutkimusmenetelmiä. Tutkimusmenetelmänä käytettiin laadullista tutkimusta, jossa haastateltiin kahta suomalaista suhteellisen menestynyttä mobiilialan yritystä. Yhteenvetona tuloksista kävi ilmi, että hyvin optimoidut tekstisisällöt nostavat sovelluksen sijoitusta Google Playn hakutuloksissa merkittävästi. Erityisen tärkeää on kuitenkin huomioida, millaisissa tapauksissa sijoituksen parannus tapahtuu, koska sillä on olennainen merkitys näkyvyyden parantumisen kannalta. Mikäli hyvät avainsanat on valittu ja tekstisisällöt optimoitu, se voi kasvattaa mobiilisovelluksen kauppasivulle tuomaa liikennettä moninkertaiseksi. Tutkimushavainnoista kävi myös ilmi, että sovelluksen kauppasivun visuaaliset elementit, kuten esittelyvideo, kuvat ja sovelluksen ikoni, ovat merkittävämpiä konversioon vaikuttavia tekijöitä kuin tekstisisältö. Hyvänä jatkotutkimuksen aiheena voisikin olla nämä asiat. Myös vastine Applen App Storesta voi olla hyvä jatkotutkimuksen aihe.This study examined keyword optimization on Google Play’s platform. Knowing that mobile applications are much competed business and lack of theses in Finnish about keyword optimization on application store, the authors wanted to take the opportunity to help mobile developers. Keyword optimization is a part of application store optimization techniques, often referred to as ASO, which in turn is a part of application marketing procedures. The aim of the study is to develop the know-how of keyword optimization practices. The theoretical background is based on e-books, professional blogs, articles and published guides of renowned experts at digital marketing. The study also includes some book sources which discuss the research methodology and the theory of consumer buying behavior supporting the study as a whole. Qualitative research method was chosen and hence two successful Finnish mobile application companies were interviewed about their ASO practices. To conclude the findings, it can be said that well-optimized text parts result in a substantially better search rank on Google Play. It is important to note, however, that the key is where this better ranking occurs as it determines the significance of improved visibility. That being said, improved visibility in appropriate occasions can multiply traffic to Google Play application landing page. The study also indicates that the visual elements of application landing page, such as video, pictures and application icon, have a more prominent role in the conversion of potential user than texts. Focus on these elements could be a good further study. Another follow-up research could be a study about Apple App Store in comparison with Google Play

Airborne remote sensing as a tool for monitoring topographical and hydrological changes on northern degraded and restored peatlands

Abstract This doctoral thesis aims to review methods which use high-resolution remote sensing (RS) to evaluate the changes in degraded and restored northern peatlands and to test and develop these topo-hydrological methods. A significant share of peatlands worldwide is degraded and encountered subsidence due to land use and drainage. Recently, activities have been directed increasingly to mitigating environmental impacts and to restoration. Understanding the state and characteristics of degradation, as well as monitoring restoration success, is important in the sustainable management of peatlands. Conventionally, the state of peatlands has been monitored using laborious field surveys that are poorly suited for monitoring larger areas. Monitoring the internal heterogeneity of the site or larger regional, national or international areas requires more applicable methods. This thesis reviews the available remote sensing methods to observe the land cover, water flow routes, and surface soil moisture on peatlands. In addition, the magnitude and impacts of topographical changes on peatland hydrology were demonstrated at eight sites. The analysis showed the subsidence of cultivated peatlands, which have caused a spread of annual river floods by 101–194% over the last 24–51 years. On forestry-drained peatlands, topographic flow accumulation and wetness indices showed that restoration increased the site wetness by 2.9–6.9% and decreased its deviation by 13–15% 1–10 months after the restoration. The methods used emphasized the determinative role of topography in the hydrological conditions of peatlands. RS is well applicable in peatland monitoring, providing advanced large-coverage and/or high-detail monitoring data. Each method, however, includes specific technical challenges and development needs, and field measurements will also be needed in the future to support the remote sensing data and analysis. The production of the data might be laborious and require adjunct resources. For many areas, open data, such as national aerial imageries and digital terrain models, can be utilized. The reviewed RS methods can be used to study the hydrological and topographical attributes specific to each peatland use. The results from the sites can be applied to guide agricultural land use management and develop restoration practices.Tiivistelmä Tämän väitöskirjan tarkoituksena on koota tarkan resolution kaukokartoitusmenetelmiä soiden kuivatuksesta ja ennallistamisesta aiheutuneiden muutosten arvioimiseen sekä testata ja kehittää valittuja topo-hydrologisia menetelmiä. Merkittävä osuus maailman soista on häiriintynyt, ja maa on painunut maankäytön ja kuivatuksen seurauksena. Toimintaa on alettu suunnata yhä enemmän ympäristövaikutusten lieventämiseen ja ennallistamiseen. Soiden muuttuneen hydrologian ymmärtäminen ja toisaalta toteutettujen toimenpiteiden onnistumisen arviointi ovat soiden tavoitteidenmukaisen ja kestävän käytön edellytys. Perinteisesti soita on seurattu työläillä kenttämenetelmillä. Suon sisäisen vaihtelun kattaviin sekä alueellisiin, kansallisiin ja kansainvälisiin seurantoihin tarvitaan soveltuvampia menetelmiä. Tässä väitöskirjassa kootaan kaukokartoitusmenetelmiä maanpinnan peitteen sekä veden kulkureittien ja suon pintakosteuden tarkastelemiseen. Lisäksi maanpinnan korkeusaseman muutosten vaikutuksia suon hydrologialle demonstroitiin kahdeksalla tutkimuskohteella. Turvepelloilla testattiin menetelmää, joka osoitti turvemaiden painumisen aiheuttaneen viereisen joen vuotuisen tulvan peittämän alueen laajentuneen 101–194 % kuluneiden 24–51 vuoden aikana. Metsätaloutta varten ojitetuilla soilla puolestaan todettiin topografisten virtauskertymien ja märkyysindeksien avulla ennallistamisen lisänneen tutkimusalueiden keskimääräistä märkyyttä 2.9–6.9 % sekä pienentäneen sen vaihteluväliä 13–15 % 1–10 kk aikana ennallistamisen jälkeen. Testatut menetelmät tähdensivät topografian merkitystä hydrologisten olosuhteiden määräytymisessä. Kaukokartoitus soveltuu hyvin soiden tilan seurantaan ja sillä saadaan tuotettua kattavia tarkan resoluution aineistoja. Kuhunkin menetelmään kuitenkin liittyy omat tekniset haasteensa ja kehitystarpeensa, ja kenttämittauksia tarvitaan myös jatkossa kaukokartoitusaineistojen ja -analyysien tukena. Aineistojen tuottaminen voi olla työlästä ja vaatia lisäresursseja. Monilla alueilla on mahdollista hyödyntää valmiita, avoimia aineistoja kuten kansallisia ilmakuvakokoelmia ja korkeusmalleja. Koottuja menetelmiä voidaan hyödyntää soiden erilaisiin käyttömuotoihin liittyvissä topografisissa ja hydrologisissa tutkimuksissa. Tutkimuskohteilta saatuja tuloksia voidaan käyttää ohjaamaan soiden maankäyttöä ja kehittämään ennallistamismenetelmiä

Maan painuminen Pohjois-Pohjanmaan säännösteltyjen jokien tulvapelloilla

Maan painuminen on vesistöjen läheisyydessä viljelytoimintaa haittaava ongelma. Tässä diplomityössä tutkittiin säännöstelyn ja tulvapeltojen viljelyn välistä vuorovaikutussuhdetta Kala- ja Siikajoen tulvapelloilla sekä painumista ilmiönä, sen syitä ja seurauksia. Tulviminen, sinänsä luonnollinen ilmiö tasaisella Pohjanmaalla, koetaan herkästi säännöstelytoiminnan epäonnistumisena, vaikka todellisuudessa säännöstelyn avulla pystytään leikkaamaan tulvahuippuja jossain määrin. Viljelysmaiden tulvahaittojen koetaan kasvaneen siitä huolimatta, että tulvanaikaista vedenkorkeutta on pyritty pienentämään säännöstelyä kehittämällä. Valtaosan maanpinnan vajoamisesta aiheuttaa viljelysmaan kuivatuksesta johtuva primäärinen konsolidaatiopainuminen. Työssä esitetään, että kuivatuksen lisäksi painumiseen vaikuttaa maanviljelystoimenpiteiden aiheuttama maaperän tiivistyminen. Maanpinta voi painua myös viljelysmaan negatiivisen ainetaseen vuoksi, jolloin pellolta poistuu ainetta esimerkiksi pintaeroosion tai orgaanisen aineksen hajoamisen johdosta. Työn tavoitteena oli maanpinnan korkeusasemia vertaamalla määrittää tutkimusalueilla maan painumisnopeudet. Maan painumista tutkittiin vertaamalla arkistosta valittujen kuivatuskarttojen maanpinnan korkeustietoja Maanmittauslaitoksen laserkeilausaineistoon. Painuneiden pisteiden keskipainumavauhti oli Siikajoen Kaivosojalla 11 mm/v vuosina 1982–2009, Lamujoen Junnonojalla 6 mm/v 1962–2013, Kalajoen Huokumaanojalla 5 mm/v 1959–2009 ja Kalajanjoen Herralanpurolla 8 mm/v 1990–2014. Pahimmilla alueilla vastaavat painumavauhdit olivat karkeasti Kaivosojalla 25 mm/v, Junnonojalla 10 mm/v, Huokumaanojalla 15 mm/v ja Herralanpurolla 25 mm/v. Maalajin vaikutusta painumiseen tarkasteltiin 1:200 000 maaperäkartan avulla. Painuminen oli suurinta paksujen turvekerrosten alueilla ja sitä suurempaa, mitä suurempi kerroksen paksuus oli. Saaduista painumanopeuksista määritettiin tutkimusalueille painumamallit, joiden avulla painumisen aiheuttamaa tulva-alueen leviämistä pystyttiin arvioimaan. Kaivosojalla tulva on levinnyt 8,8 ha, Junnonojalla 4,7 ha ja Herralanpurolla 12 ha kuivatussuunnitelman ja laserkeilausvuoden välillä maan painumisen takia. Seuraavan 20 vuoden aikana tulva tulee leviämään vielä lisää Kaivosojalla 17 ha (yht. 26 ha), Junnonojalla 3,8 ha (yht. 8,5 ha) ja Herralanpurolla 29 ha (yht. 41 ha), jos painumisolosuhteissa ei tapahdu muutoksia. Siika- ja Lamujoella tulos yleistettiin karkeasti koskemaan vuotuisen tulvan leviämistä koko jokivarren alueella tulvariskikarttoja apuna käyttäen. Siikajoella vuotuinen tulva on levinnyt 130 ha ja tulee seuraavan 20 vuoden aikana leviämään vielä lisää 250 ha (yht. 380 ha). Lamujoella puolestaan vuotuinen tulva on levinnyt 90 ha ja tulee leviämään vielä lisää 73 ha (yht. 160 ha). Diplomityön osana suoritettiin myös kyselytutkimus, jonka tavoitteena oli selvittää, miten maanviljelijät kokevat tulvan ja sen aiheuttaman haitan. Maanviljelijöiden mielestä tulvan vaikutukset ovat kasvaneet viimeisen 20 vuoden aikana. Tilastot kuitenkin osoittavat, että tulvien keskimääräinen suuruus on hieman laskenut. Maan painumisen johdosta tulva-alueet kasvavat jokivarsien pelloilla, vaikka tulvavedenkorkeus pysyisi samana. Painumisella on suuri merkitys tulva-alueiden laajenemiseen nyt ja tulevaisuudessa. Merkittävä osuus Pohjanmaan jokivarsien pelloista sijaitsee tulvariskialueilla. Ilman aktiivisia toimenpiteitä ongelma ei ratkea, vaan pahenee jatkuvasti ajan kuluessa. Ongelmaa voidaan yrittää ratkaista joko tulvia vähentämällä, painumista ehkäisemällä tai siirtämällä maanviljelytoiminta pois tulvariskialueilta.Subsidence causes trouble on the fields next to watercourses. The interaction between regulating waterways and farming the flood fields in the Kalajoki and Siikajoki areas and the phenomena of subsidence as well as the reasons and the consequences were studied in this master’s thesis. Flooding is a natural phenomenon in the flat areas of Ostrobothnia but it is still often experienced as a failure of regulation practices. The increasing flood damage are experienced on the fields regardless of the reduction in the flood water levels achieved by development of the regulation. Most of the subsidence is caused by the primary consolidation related to the improvements of drainage. It is proposed in the study that also compaction due to the farming activities increases the subsidence. In addition, a negative mass balance of the fields caused by surface erosion or organic matter degradation might also influence. The aim of the study was to define the subsidence rates for the target fields by comparing the ground altitudes in time and space. The subsidence was studied by comparing the altitudes in the drainage scheme maps chosen from the archives and laser scanning data by the National Land Survey of Finland. The average rate was 11 mm/year in the Kaivosoja study target by the river Siikajoki between 1982–2009, 6 mm/year in Junnonoja (Siikajoki river) 1962–2013, 5 mm/year in Huokumaanoja (Kalajoki river) 1959–2009 and 8 mm/year in Herralanpuro (Kalajanjoki river) 1990–2014. The rates in the most problematic areas were roughly 25 mm/year in Kaivosoja, 10 mm/year in Junnonoja, 15 mm/year in Huokumaanoja and 25 mm/year in Herralanpuro. The effect of the soil type on the subsidence was studied by the soil map 1:200 000. The highest rates were found in the areas of thick peat layers and the subsidence was greater in the thicker peat layer. Subsidence models were formed by using the subsidence rates to evaluate the spread of the flooding area. A typical flood has spread 8,8 ha in Kaivosoja, 4,7 ha in Junnonoja and 12 ha in Herralanpuro due to the subsidence between the years of the drainage map and the laser scanning. The flood will spread 17 ha more (26 ha in total) in Kaivosoja, 3,8 ha more (8,5 in total) in Junnonoja and 29 ha more (41 ha in total) in Herralanpuro in the following 20 years if there won’t be any changes in the subsidence conditions. The results were generalized to cover the spread of the annual flood in the whole Siikajoki and Lamujoki river areas by using the flood hazard maps. The annual flood has spread 130 ha and will spread 250 ha more (380 ha in total) in the next 20 years by the Siikajoki river. The spread has been 90 ha and will be 73 ha more (160 ha in total) in the next 20 years by the Lamujoki river. A survey study was also performed to find out how the farmers experience the flooding and the harm caused by it. According to the answers the flood hazard has increased during the past 20 years. The statistics however show that the average magnitude of the floods has actually decreased. Despite the constant flood water level the field areas covered by water are growing because of the subsidence. The subsidence affects the spread of the flood now and in the future. A significant share of the fields in the Ostrobothnia area is located in the flood hazard areas. Without active moves the problem won’t be solved. A solution could be developed either by reducing the floods, by preventing the subsidence or by moving the farming business out of the flood hazard areas

Thermal Isomerization of Hydroxyazobenzenes as a Platform for Vapor Sensing

Photoisomerization of azobenzene derivatives is a versatile tool for devising light-responsive materials for a broad range of applications in photonics, robotics, microfabrication, and biomaterials science. Some applications rely on fast isomerization kinetics, while for others, bistable azobenzenes are preferred. However, solid-state materials where the isomerization kinetics depends on the environmental conditions have been largely overlooked. Herein, an approach to utilize the environmental sensitivity of isomerization kinetics is developed. It is demonstrated that thin polymer films containing hydroxyazobenzenes offer a conceptually novel platform for sensing hydrogen-bonding vapors in the environment. The concept is based on accelerating the thermal cis-trans isomerization rate through hydrogen-bond-catalyzed changes in the thermal isomerization pathway, which allows for devising a relative humidity sensor with high sensitivity and quick response to relative humidity changes. The approach is also applicable for detecting other hydrogen-bonding vapors such as methanol and ethanol. Employing isomerization kinetics of azobenzenes for vapor sensing opens new intriguing possibilities for using azobenzene molecules in the future.Peer reviewe

Thermal Isomerization of Hydroxyazobenzenes as a Platform for Vapor Sensing

Photoisomerization of azobenzene derivatives is a versatile tool for devising light-responsive materials for a broad range of applications in photonics, robotics, microfabrication, and biomaterials science. Some applications rely on fast isomerization kinetics, while for others, bistable azobenzenes are preferred. However, solid-state materials where the isomerization kinetics depends on the environmental conditions have been largely overlooked. Herein, an approach to utilize the environmental sensitivity of isomerization kinetics is developed. It is demonstrated that thin polymer films containing hydroxyazobenzenes offer a conceptually novel platform for sensing hydrogen-bonding vapors in the environment. The concept is based on accelerating the thermal <i>cis</i>–<i>trans</i> isomerization rate through hydrogen-bond-catalyzed changes in the thermal isomerization pathway, which allows for devising a relative humidity sensor with high sensitivity and quick response to relative humidity changes. The approach is also applicable for detecting other hydrogen-bonding vapors such as methanol and ethanol. Employing isomerization kinetics of azobenzenes for vapor sensing opens new intriguing possibilities for using azobenzene molecules in the future

Peatland subsidence enhances cultivated lowland flood risk

Abstract Peatlands worldwide are being threatened by intensive land use and drainage, which leads to soil subsidence. This has consequences for farming, especially on low-gradient cultivated peat-dominated lowlands with high flood risk. In this study, we combined historical soil elevation data and new lidar data to improve the estimation of subsidence and its consequences for lowland river systems. The results showed 202−349 mm subsidence within the last 24–51 years, with a mean rate of 5.15–9.47 mm y⁻¹ for riparian peatland on the west coast of Finland. The subsidence rate was partly explained by the depth of the organic soil layer (R² = 0.710, p &gt; 0.05). The results also showed that increasing flooding of cultivated fields is mainly due to soil subsidence, not to increased flooding occurrence in river systems. The area flooded annually was found to increase by 101–194 % for the last 24–51 years, due to soil subsidence near rivers. Generalization of the results to catchment scale indicated an increase in the annual flood zone of 45 % in cultivated fields in one of two study catchments (Siikajoki river basin). These results demonstrate the value of using historical data to study soil subsidence and confirm that the risk of flooding increases in cultivated organic lowlands due to intensive drainage and subsidence. New management strategies, such as peatland rewetting, restoration, and paludiculture, should be considered in future land use plans to reduce subsidence and provide new income streams for farmers

Unmanned Aircraft System (UAS) Structure-From-Motion (SfM) for monitoring the changed flow paths and wetness in minerotrophic peatland restoration

Peatland restoration aims to achieve pristine water pathway conditions to recover dispersed wetness, water quality, biodiversity and carbon sequestration. Restoration monitoring needs new methods for understanding the spatial effects of restoration in peatlands. We introduce an approach using high-resolution data produced with an unmanned aircraft system (UAS) and supported by the available light detection and ranging (LiDAR) data to reveal the hydrological impacts of elevation changes in peatlands due to restoration. The impacts were assessed by analyzing flow accumulation and the SAGA Wetness Index (SWI). UAS campaigns were implemented at two boreal minerotrophic peatland sites in degraded and restored states. Simultaneously, the control campaigns mapped pristine sites to reveal the method sensitivity of external factors. The results revealed that the data accuracy is sufficient for describing the primary elevation changes caused by excavation. The cell-wise root mean square error in elevation was on average 48 mm when two pristine UAS campaigns were compared with each other, and 98 mm when each UAS campaign was compared with the LiDAR data. Furthermore, spatial patterns of more subtle peat swelling and subsidence were found. The restorations were assessed as successful, as dispersing the flows increased the mean wetness by 2.9–6.9%, while the absolute changes at the pristine sites were 0.4–2.4%. The wetness also became more evenly distributed as the standard deviation decreased by 13–15% (a 3.1–3.6% change for pristine). The total length of the main flow routes increased by 25–37% (a 3.1–8.1% change for pristine), representing the increased dispersion and convolution of flow. The validity of the method was supported by the field-determined soil water content (SWC), which showed a statistically significant correlation (R2 = 0.26–0.42) for the restoration sites but not for the control sites, possibly due to their upslope catchment areas being too small. Despite the uncertainties related to the heterogenic soil properties and complex groundwater interactions, we conclude the method to have potential for estimating changed flow paths and wetness following peatland restoration